Mung bean sweet soup

Ingredientsserves 4

Method

1. Wash the beans. To hurry the sand use one of the three Hong Kong tricks: freeze the soaked beans in their water overnight; or dry-fry the washed beans and rice in a wok until hot to the touch, splash in two tablespoons of hot water and keep tossing until it smokes; or plan to shock the pot with iced water later.
2. Bring seven cups of water (about 1.75 litres) to a rolling boil, add the beans, the rice and the scraped peel, lid on, and boil ten minutes.
3. Turn to medium-low and simmer forty to sixty minutes, stirring now and then. If the beans are slow to split and the skins float, pour in a cup of iced water, bring it back to the boil and repeat twice; the shock cracks the skins. If it is still not sandy, press a ladleful through a sieve as for red bean soup.
4. The kelp: soak the dried kelp thirty minutes, rinse off the grit and the white bloom, and cut it in short strips; it goes in for the last fifteen minutes only, after the beans have broken down, or it melts into slime.
5. The rue: a small bunch, washed, on the stem, in with the kelp; fifteen minutes gives its scent, longer turns the pot medicinal and too much does the same. Many families find it too strong and leave it out, and it is still mung bean soup.
6. Add the rock sugar and let it dissolve, then a small pinch of salt, which takes the sea taste off the kelp and makes the sweetness stand out.
7. Fish out the rue before serving. Hot is fine; in summer cool it and put it in the fridge, and cold from the fridge is the Hong Kong way.

Take care

• None of the declared allergens. Rue is used as a small bunch and taken out after cooking; in quantity it is not a food. Kelp contains iodine, which Australian dried-kelp packs state on the label.

The story

Mung bean soup is the summer twin of red bean soup, and the pair are the 二沙, the two sands, that anchor every dessert-shop menu. The kelp and the rue are the Hong Kong signature that Guangzhou does not share, and the smell of rue in the stairwell was how a neighbour knew what was on the stove. The dessert shop's smoothness comes from grinding the cooked beans; at home that is the press through a sieve.

Same wall

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Lo Fo Tong is cultural food-heritage reference, not medical advice. If you are pregnant, unwell or on medication, talk to your doctor or registered practitioner before changing what is in the pot.