Sweet Mung Bean Soup (绿豆汤): The Classic Chinese Summer Cooler

When the heat becomes too much, a huge pot of this is what appears on stoves across southern China. Sweet mung bean soup — lǜ dòu tāng — is the original summer cooler: tiny green beans simmered until soft, lightly sweetened, and served ice-cold from the fridge. It's the bowl people grew up reaching for on the hottest afternoons, and once you've had it cold on a sweltering day, you'll understand exactly why.

It couldn't be simpler to make — really just beans, water, and a little rock sugar — but there's one fork in the road worth knowing about before you start, because it changes the whole character of the bowl. More on that in a second.

Two ways to make it — pick your texture

This is the part most recipes skip, and it's the difference between a good bowl and a disappointing one. Mung bean soup goes two directions, depending on how you cook it:

• Clear and refreshing (清绿汤). A thinner, greenish, brothy soup where the beans stay mostly whole. This is the lighter, more cooling version — the one most associated with beating the summer heat. The trick is a shorter cook so the beans don't fully burst.
• Thick and creamy (起沙). A cloudier, heartier soup where the beans break down and "bloom" into a soft, almost porridge-like texture. Richer and more filling. The trick is a longer cook, and stirring to help the beans break apart.

Neither is more correct — it's purely preference. I'll give you the method for both below.

Ingredients

Makes about 4–6 servings

• 200g (about 1 cup) dried mung beans (绿豆)
• 60–80g rock sugar (冰糖), to taste
• About 1.5–2 liters (6–8 cups) water
• Optional: a small piece of dried tangerine peel (陈皮) for a subtle fragrant note

How to make it

1. Rinse and (optionally) soak. Rinse the mung beans under cool water and discard any that float. Soaking them for an hour or two shortens the cooking time, but it isn't essential — you can cook them straight from dry.

2. Bring to a boil. Add the beans and water to a pot and bring to a boil, then lower to a steady simmer. Skim off any foam that rises in the first few minutes.

3a. For the CLEAR version: Simmer gently for about 20–25 minutes, until the beans are just tender but still mostly holding their shape and the liquid is greenish. Don't overcook. Some people pour off and chill this lighter "broth" separately for the most cooling drink.

3b. For the THICK version: Keep simmering for 40–60 minutes total, stirring now and then, until the beans burst open and the soup turns cloudy and soft. Add a splash more water if it gets too thick.

4. Sweeten. Once the beans have reached the texture you want, stir in the rock sugar until dissolved. Taste and adjust — it should be lightly sweet, not syrupy.

5. Chill and serve. Let it cool, then refrigerate for at least 2–3 hours. Serve cold. In high summer, a few ice cubes in the bowl are very welcome.

Tips

• Serve it cold. This is a chilled soup at heart. It's fine warm, but cold from the fridge on a hot day is the whole point.
• Freeze it into popsicles. Pour the sweetened soup into popsicle molds for an easy frozen treat — kids love these, and it's a great use for a big batch.
• Don't over-sweeten. Start with less sugar than you think; you can always add more, and the beans' own flavor should still come through.
• It keeps well. Stored in the fridge, it's good for 3–4 days — make a big pot and have it on hand all week.