Growing up in Macau and Hong Kong, sweet mung bean soup (綠豆沙) was one of the most popular Cantonese dessert soups my family enjoyed during the hot summer months. Lightly sweet, refreshing, and nourishing, this traditional Chinese sweet soup is often served warm in the winter or chilled during warmer weather. Made with green mung beans, dried seaweed, and sugar, this authentic sweet mung bean soup recipe tastes just like the classic tong sui (糖水) served in Hong Kong dessert shops.
Also known as luk dau sa (綠豆沙), sweet green mung bean soup is a beloved Cantonese dessert alongside favorites such as sweet red bean soup, black sesame soup, taro sago, black glutinous rice dessert, almond jelly, and mango pomelo sago. This easy homemade recipe includes both Instant Pot and stovetop methods, making it simple to prepare no matter which cooking method you prefer. Follow the step-by-step photos and video tutorial to learn how to make authentic Chinese sweet mung bean soup at home.
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What is mung bean soup?
Sweet mung bean soup is a classic Chinese dessert soup made from green mung beans, sugar, and water. While mung beans are often used in savory dishes such as lotus root pork soup and zongzi, they are most commonly enjoyed in a sweet dessert known as mung bean soup. In Chinese cuisine, this type of sweet soup is called tong sui (糖水), which literally means "sugar water." Tong sui desserts are traditionally served after family meals, at Chinese banquets, or as a refreshing snack on warm days.
In Cantonese, sweet mung bean soup is known as luk dau sa (綠豆沙) when the beans are cooked until creamy and partially broken down. In Mandarin, it is often called lu dou tang (綠豆湯), which translates to mung bean soup. Depending on the region and personal preference, the texture can range from smooth and thick to light and brothy.
One reason this dessert is so popular is its versatility. It can be served warm during cooler months or chilled on hot summer days. Growing up in Macau and Hong Kong, my family often enjoyed cold mung bean soup as a refreshing treat during the summer. For a fun variation, you can even freeze the soup into homemade popsicles for a cool and delicious dessert.
Why You'll Love This Sweet Mung Bean Soup
- Authentic Cantonese tong sui dessert
- Only 4 simple ingredients
- Instant Pot and stovetop instructions
- Naturally vegan and dairy-free
- Serve hot or cold
- Great make-ahead dessert
What Does Sweet Mung Bean Soup Taste Like?
Sweet mung bean soup has a mild, earthy, and slightly nutty flavor with a gentle sweetness from brown sugar or rock sugar. The mung beans become soft and creamy as they cook, creating a comforting texture that can be either thick and smooth or light and brothy, depending on how long the beans are simmered.
In traditional Cantonese-style sweet mung bean soup, dried seaweed is often added, giving the dessert a subtle aroma and extra depth of flavor without making it taste like the ocean. The sweetness is usually light and balanced, allowing the natural flavor of the mung beans to shine through.
When served warm, sweet mung bean soup is cozy and comforting. When chilled, it becomes a refreshing dessert that is especially popular during hot summer months in Hong Kong, Macau, and southern China. If you enjoy desserts such as sweet red bean soup, black glutinous rice dessert, black sesame soup, taro sago, and mango sago polmeon, you'll likely enjoy the delicate flavor and creamy texture of sweet mung bean soup as well.
What are green mung beans?
Green mung beans are small legumes scientifically known as Vigna radiata. They are also commonly called green gram or Chinese green beans. These tiny, oval-shaped beans have a bright green outer skin and belong to the legume family, and are widely cultivated and consumed throughout Asia.
Mung beans are highly versatile and can be enjoyed in several forms. They can be cooked whole, split into halves (known as mung dal), or sprouted into crunchy mung bean sprouts. When cooked, green mung beans develop a mild, slightly sweet, and earthy flavor with a soft, creamy texture, similar in comfort to dishes like Cantonese savory zongzi.
Mung bean sprouts are especially popular in Asian cooking and are commonly used in salads, stir-fries, and noodle dishes such as chicken yi mein, soy sauce noodles, and beef chow fun. Because of their light flavor and nutritional value, green mung beans are a staple ingredient in many traditional Chinese and other Asian dishes, both savory and sweet.
What Are the Benefits of Mung Bean Soup?
From a traditional Chinese medicine perspective, mung bean soup is considered a cooling food that helps balance the body's internal "heat" or yang energy. Green mung beans are believed to help clear excess "heat" from the body, support the flow of qi (energy), and promote overall internal balance.
Because of these cooling properties, mung bean soup is commonly enjoyed during hot summer months in China, Hong Kong, and other parts of Asia. It is traditionally believed to help reduce internal heat, support hydration, and provide relief from discomfort caused by hot weather, including the risk of heat exhaustion or heat stroke.
Beyond their traditional beliefs, mung beans are naturally rich in plant-based protein, fiber, and antioxidants, making mung bean soup a nourishing, light dessert option.
However, in traditional Chinese medicine, mung bean soup is generally considered less suitable for individuals with a "cold" or weak constitution, as its cooling nature may further lower internal warmth. From a modern dietary perspective, it is also best enjoyed in moderation, since legumes can sometimes cause bloating or digestive discomfort in sensitive individuals.
Overall, mung bean soup is valued both as a comforting dessert and as a cooling, seasonal dish, especially in warm weather.
What Is the Difference Between Mung Bean Soup and Red Bean Soup?
Mung bean soup and red bean soup are both classic Chinese tong sui (糖水) dessert soups, but they differ in flavor, texture, cooking properties, and traditional health concepts.
1. Main ingredient and flavor
Mung bean soup is made from green mung beans and has a light, mildly sweet, and slightly earthy flavor. Red bean soup is made from adzuki beans (red beans) and has a deeper, naturally sweeter, and more "nutty" flavor. Overall, red bean soup tastes richer and more dessert-like, while mung bean soup is lighter and more refreshing.
2. Texture
Mung beans cook down faster and can become soft, creamy, and slightly loose in texture. Red beans hold their shape a bit more and create a thicker, denser, and more porridge-like consistency when fully cooked.
3. Traditional Chinese medicine perspective
In traditional Chinese medicine, mung bean soup is considered a "cooling" food that helps reduce internal heat, making it especially popular in summer. Red bean soup is considered more neutral or slightly warming and is often enjoyed year-round as a nourishing dessert.
4. Cooking time and preparation
Mung bean soup generally cooks faster, especially in an Instant Pot, and may not require soaking. Red beans usually need longer soaking and cooking times to become soft and creamy.
5. Popular variations and use
Mung bean soup is often served plain or lightly sweetened and sometimes chilled or even frozen into popsicles. Red bean soup is commonly used in richer desserts such as red bean paste and shaved ice toppings (Hawaiian shave ice and Asian shaved ice), and is served warm with glutinous rice balls (tang yuan), pan-fried rice cakes, red bean drink, and red bean mochi.
In summary, mung bean soup is light, refreshing, and cooling, while red bean soup is richer, sweeter, and more comforting-both are beloved staples of traditional Chinese dessert culture.
Is mung bean soup served hot or cold?
Sweet mung bean soup (綠豆沙) is traditionally enjoyed both hot and cold. During the summer, many families in Hong Kong and southern China chill the soup and serve it cold as a refreshing dessert on hot days. In cooler weather, it's commonly served warm as a comforting bowl of tong sui (Chinese sweet dessert soup). No matter how you serve it, the creamy mung beans and lightly sweet flavor make it a delicious treat year-round.
Do I need to soak mung beans before cooking?
When you use a pressure cooker, you don't need to soak it before. Just wash the green mung beans and put them in an Instant Pot. If you are using a stovetop or slow cooker, it's best to soak them for 2-4 hours beforehand. So, it doesn't take as long to cook them.
What Are the Ingredients for Chinese Mung Bean Soup?
Chinese mung bean soup is a simple dessert made with just a few basic ingredients, but its flavor and style can vary by region.
In Hong Kong and Guangzhou (Cantonese cuisine), mung bean soup is often prepared as a sweet dessert soup and sometimes includes dried seaweed. The seaweed adds a subtle aroma and depth of flavor without overpowering the natural taste of the mung beans. In these regions, the soup is typically sweeter and enjoyed as a classic tong sui (糖水), especially during hot summer months.
In contrast, when I traveled to Shanghai and northern China, I noticed that mung bean soup was usually less sweet and often made without seaweed. It was more commonly served as a light, everyday drink or even enjoyed for breakfast alongside steamed buns (mantou 饅頭). The texture is often lighter and more broth-like compared to the thicker Cantonese-style dessert version.
For this sweet mung bean soup recipe, the main ingredients are very simple:
- Water - the base of the soup
- Green mung beans - the main ingredient, providing a soft and creamy texture when cooked
- Dried seaweed (optional) - adds aroma and a subtle umami depth, commonly used in Cantonese-style versions
- Brown sugar - provides gentle sweetness and a rich caramel-like flavor
Traditionally, brown slab sugar or rock sugar is preferred because it melts slowly and gives the soup a deeper, more complex sweetness. However, regular brown sugar works well as a substitute when slab sugar is unavailable.
Overall, mung bean soup is a versatile dish that reflects regional differences across China-from a lightly sweet breakfast drink in the north to a richer dessert soup in southern Cantonese cuisine.
Ingredient Substitutions:
Can I use other sugar?
Yes, sure. Traditionally, people like to use rock sugar (冰糖), which creates a cleaner, lighter sweetness. It is commonly used in Chinese dessert soups and gives the mung bean soup a more authentic tong sui flavor. You can use brow sugar slab or brown sugar. Remember to adjust the amount of sugar depending on your preferred sweetness level.
Can I make mung bean soup without seaweed?
Of course! Dried seaweed is optional and mainly used in Cantonese-style mung bean soup to add aroma, texture, and depth. If you don't have it, you can skip it without affecting the soup's core flavor.
Is it ok to cook on the stove or in a slow cooker?
If you don't have an Instant Pot, you can cook mung bean soup on the stovetop by simmering until the beans are soft and creamy. Or, use a slow cooker. Conversely, if you prefer a faster method, the Instant Pot significantly reduces cooking time while still producing a rich, smooth texture.
Storage:
How To Store Sweet Mung Bean Soup?
Sweet mung bean soup stores very well, making it a great make-ahead dessert you can enjoy throughout the week.
Refrigerator storage:
Let the mung bean soup cool completely before transferring it to an airtight container. Store it in the refrigerator for up to 3-4 days. The soup will naturally thicken as it chills, so you can add a little water when reheating to loosen the texture if needed.
Can I freeze mung bean soup?
You can also freeze mung bean soup for longer storage. Pour it into freezer-safe containers or silicone molds and freeze for up to 1-2 months. This is also a fun way to make homemade mung bean popsicles for a refreshing summer treat.
Reheating tips:
Reheat on the stovetop over low heat or in the microwave until warm. Stir well and adjust the sweetness or consistency by adding a small amount of water if the soup has thickened too much during storage.
Cooking Tips & Troubleshooting: (From My Kitchen)
Over the years of making sweet mung bean soup (綠豆沙), I've learned a few small tricks that make a big difference in texture and flavor. These tips will help you avoid common mistakes and get that smooth, creamy Hong Kong-style result every time.
Cooking Tips:
1. Prepare the dried seaweed (optional)
Rinse and soak dried seaweed for a few minutes to remove any impurities. You can cut it into smaller pieces before cooking. If you are using kombu-style seaweed, slice it into thin strips for even cooking and better texture in the soup.
2. Wash the mung beans
Rinse green mung beans thoroughly under cold water until the water runs clear. If you are using an Instant Pot or a pressure cooker, soaking is optional.
3. Soak for stovetop or slow cooker (recommended)
If you are cooking on the stovetop or using a slow cooker, soak the mung beans for 2-4 hours before cooking. This helps soften the beans and reduces cooking time, making the texture creamier.
4. Instant Pot method (quick and easy)
Add mung beans, water, and seaweed into the Instant Pot. Close the lid and set the valve to sealing. Cook on high pressure for 45 minutes, then allow a quick release. The beans should be soft and slightly broken down, creating a naturally creamy soup base.
5. Stovetop method (traditional style)
Add about 7 cups of water to the pot along with the mung beans and seaweed. Bring to a boil, then reduce to a gentle simmer for 1.5-2 hours, or until the beans are soft and start to break apart. Stir occasionally and add more water if needed.
Troubleshooting:
Why is my soup too watery?
Simmer uncovered for 10-20 minutes to reduce liquid, or mash more beans to naturally thicken it.
Why did my soup turn too thick, like paste?
Add hot water a little at a time until you reach your desired consistency.
What should I do? My soup tastes bland.
Try adding a little more sugar.
People Also Ask:
Red mung beans are also called adzuki or red beans because their outer skin is red. On the other hand, green mung beans are called that because their outer shells are green. Adzuki beans are bigger than green mung beans.
Normally, I will refrigerate them. And, I eat them cold or warm them up in a microwave. Also, I like to freeze them as popsicles.
I prefer to use this dried seaweed like miso soup because it is softer. Some like to use kombu, which is an edible kelp. They are on a sheet and a little harder, so they take longer to soak.
Remember, both dried seaweeds require washing and soaking before using.
Instructions for How to Make Chinese Sweet Mung Bean Soup (Luk Dau Sa) Instant Pot:
1. First, wash and soak ¼ cup of dried seaweed (2 g) for a couple of minutes.
2. Then, wash 1 cup of green mung beans (8 oz) and put them into an instant pot.
3. After that, add 5 cups of water to the pressure cooker.
4. Add the soaked seaweeds to the instant pot. Close the lid and vent. Push the manual button and adjust the time to 45 minutes at high pressure. Then, quickly release pressure. (Be careful when you do the quick-release pressure.)
5. Put ¾ cups of brown sugar. (You can add more sugar to your taste.) Mix it well. It's ready to serve warm or refrigerated.
Enjoy this simple and tasty instant pot sweet mung bean soup recipe! Also check out these recipes: wonton soup, eggplant pork stir-fry, pork knuckles and ginger stew, mango popsicles, grass jelly, and white rabbit candy ice cream.
Instructions for how to make Chinese mung bean soup dessert on the top stove:
1. First, wash and soak ¼ cup of dried seaweed (2 g) for a couple of minutes.
2. Then, wash and soak 1 cup of green mung beans (8 oz) for 2-4 hours before cooking.
3. After that, put the soaked mung beans into a big pot and add 7 cups of water. Turn on medium fire. Let it cook until it's boiling. Then, turn the fire to small.
4. Next, add the soaked seaweed from step 1 into the pot. Close the lid and simmer it for 1.5-2 hours.
5. Lastly, add ¾ cups of brown sugar. (You can add more sugar to your taste.) Mix it well. It's ready to serve warm or refrigerated.
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Sweet Mung Bean Soup
Equipment
- 1 Pot or Instant pot
Video
Ingredients
- 1 cup Geen mung beans ( 8oz)
- ¼ cup Dried seaweed (2 g)
- 5 cups Water
- ¾ cup Brown sugar (Add sugar to your taste)
Instructions
Instant pot method:
- First, wash and soak ¼ cup of dried seaweed (2 g) for a couple of minutes.
- Then, wash 1 cup of green mung beans (8 oz) and put them into an instant pot.
- After that, add 5 cups of water to the pressure cooker.
- Add the soaked seaweeds to the instant pot. Close the lid and vent. Push the manual button and adjust the time to 45 minutes at high pressure. Then, quickly release pressure. (Be careful when you do the quick-release pressure.)
- Put ¾ cups of brown sugar. (You can add more sugar to your taste.) Mix it well. It's ready to serve warm or refrigerated.
Stove top method:
- First, wash and soak ¼ cup of dried seaweed (2 g) for a couple of minutes.
- Then, wash and soak 1 cup of green mung beans (8 oz) for 2-4 hours before cooking.
- After that, put the soaked mung beans into a big pot and add 7 cups of water. Turn on medium fire. Let it cook until it's boiling. Then, turn the fire to small.
- Next, add the soaked seaweed from step 1 into the pot. Close the lid and simmer it for 1.5-2 hours.
- Lastly, add ¾ cups of brown sugar. (You can add more sugar to your taste.) Mix it well. It's ready to serve warm or refrigerated.
Notes
Cooking Tips:
1. Prepare the dried seaweed (optional)
Rinse and soak dried seaweed for a few minutes to remove any impurities. You can cut it into smaller pieces before cooking. If you are using kombu-style seaweed, slice it into thin strips for even cooking and better texture in the soup.
2. Wash the mung beans
Rinse green mung beans thoroughly under cold water until the water runs clear. If you are using an Instant Pot or a pressure cooker, soaking is optional.
3. Soak for stovetop or slow cooker (recommended)
If you are cooking on the stovetop or using a slow cooker, soak the mung beans for 2–4 hours before cooking. This helps soften the beans and reduces cooking time, making the texture creamier.
4. Instant Pot method (quick and easy)
Add mung beans, water, and seaweed into the Instant Pot. Close the lid and set the valve to sealing. Cook on high pressure for 45 minutes, then allow a quick release. The beans should be soft and slightly broken down, creating a naturally creamy soup base.
5. Stovetop method (traditional style)
Add about 7 cups of water to the pot along with the mung beans and seaweed. Bring to a boil, then reduce to a gentle simmer for 1.5–2 hours, or until the beans are soft and start to break apart. Stir occasionally and add more water if needed.
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