Lǜdòu Tāng

the cooling mung bean soup of the Chinese summer: whole green beans boiled until they burst, sweetened with rock sugar, and drunk warm or chilled against the heat

Origin: China

From the journey of Mung Bean.

Chinese medicine classifies the mung bean as strongly cooling, and lǜdòu tāng is the practical application of that belief on a national scale. It is drunk through the summer months across the whole country as a specific against heatstroke and against shànghuǒ, the internal heat held to be caused by hot weather, fried food, and stress; municipalities and employers have long distributed it to outdoor workers during heatwaves, and hospitals and canteens keep vats of it going through July and August. The materia medica goes further and credits mung with countering poison, a claim that appears in Chinese pharmacological writing from the Tang period onwards and is still repeated in the household advice that mung soup should not be taken alongside medicine lest it cancel the dose. Whether or not any of that stands up, the soup itself is genuinely refreshing: thin, faintly starchy, mildly sweet, and served either warm from the pot in the north or poured over ice in Guangdong, where it is a tong sui, a sweet water. Cantonese practice often adds a strip of dried tangerine peel or a knot of kelp, and a version cooked longer until the beans dissolve entirely is served as a thick porridge for breakfast. It is amongst the plainest things in Chinese cookery and one of the most widely made.

Ingredients

Soup

  • 200 g whole green mung beans
  • 2 litre water
  • 1 piece dried tangerine peel (chenpi), soaked and scraped (optional)
  • 80 g rock sugar (bingtang), or to taste
  • 1 pinch fine salt

To Serve

  • 1 handful ice, to serve cold (optional)

Method

  1. Rinse the mung beans in cold water, discarding any that float, and drain. Soaking for a couple of hours shortens the cooking but is not required.
  2. Put the beans in a large pan with the water and the tangerine peel if using. Bring to a rolling boil, then reduce to a steady simmer and cook, partly covered, for 35 to 45 minutes.
  3. Cook until the beans have swollen, split their skins, and are entirely soft, with a proportion of them collapsed to thicken the liquid. For a clearer, thinner soup stop as soon as most have burst; for a porridge carry on another 20 minutes.
  4. Add the rock sugar and the pinch of salt, and stir over a low heat until the sugar has completely dissolved. Taste and adjust; it should be mildly sweet rather than syrupy.
  5. Serve warm in bowls, or cool completely and refrigerate and serve over ice. It thickens as it cools and can be let down with cold water.

Notes

Rock sugar gives a cleaner sweetness than granulated and is what is traditionally used, though caster sugar will do. Cantonese versions add dried tangerine peel, a small knot of kombu, or a few lily bulbs; a common northern variant cooks the beans with a handful of glutinous rice for body. For the more elaborate lǜdòu shā, sieve the cooked beans to remove the skins and cook the purée down with sugar into a smooth paste for filling mooncakes and buns. The traditional caution that mung soup counteracts medicine is folk pharmacology rather than established fact, but it is widely enough believed in China that it is worth knowing. Note that the mung bean here is the whole plant's simplest use; the sprouting and starch-extraction techniques for which China is far more significant are separate preparations entirely.

The Gastrographer

The Gastrographer

Mapping Culinary History

To explore — select an ingredient below.

Journey Point Map Key

Ingredient originTrade or transit route
Became a culinary stapleColonial / trade control
© 2026 The Gastrographer. All original research, narratives, and illustrations. All rights reserved.