A classic Cantonese slow-simmered soup (老火汤) built on kudzu root (粉葛, the starchy kind of ge-gen, Pueraria) and dace (鲮鱼, a bony Cantonese river fish also called mud carp), rounded out with rice beans (赤小豆) and a little dried tangerine peel (陈皮). The dace is pan-fried golden on both sides first, then simmered loose or tied in muslin to catch its many fine bones; over two hours the kudzu starch breaks down and thickens the broth while the fried fish turns it milky and savory. Guangdong households reach for it in the humid, sticky weather of spring and early summer, where folk food-therapy treats it as a soup that clears heat and drains damp (清热下火、祛湿). Seasoned only with salt, it drinks earthy-sweet and powdery, the kudzu falling apart into the broth.
The soup belongs to the Guangfu (Cantonese) slow-soup tradition (老火汤), a food-therapy practice the people of the Pearl River Delta have kept for centuries, shaped by Guangzhou's hot, humid climate; soups there are tuned to the season — clearing damp in spring and summer, moistening in autumn, warming in winter. Within that frame this is a workaday damp-draining soup rather than a banquet dish, so it carries no fixed founding date. Its ingredients are local: kudzu root is the powdery, sweet 'sweet-kudzu' (甘葛, 粉葛) prized for soup over the woody medicinal 柴葛, and dace (鲮鱼) is a Pearl River farm fish so common in Guangdong that it is also the base of the region's famous canned 豆豉鲮鱼. The beans are rice beans (赤小豆, the slender 饭豆), used in Chinese medicine for draining water and damp, deliberately not the round red bean (红豆) used for nourishing blood.
A bowl of pale, faintly milky broth, sweet-earthy and clean on the tongue. The kudzu has simmered until it gives way at a touch of the chopsticks, half-dissolved and powdery; the broth carries a soft, almost starchy body from it. The fried dace has handed its savor to the soup and the fine river-fish bones are why it was tied in muslin or fished out before serving. Only salt seasons it, so the sweetness is all kudzu, bean, and fish. A faint citrus lift from the tangerine peel sits behind everything.
Two things make this soup. First the kudzu: soup cooks insist on powdery sweet-kudzu (粉葛) because its starch runs near 40 percent, against roughly 20 percent in the woody 柴葛. Over a long simmer that starch gelatinizes — partly softening the root from firm to powdery and partly dissolving into the liquid, so a thin broth slowly turns full-bodied and faintly milky. Second the fish: dace is pan-fried golden on both sides first, which both browns the proteins (Maillard) for aroma and renders surface fat. When fish and hot water then boil together, the violent boiling shears the rendered fat into tiny droplets that the soup's gelatin, lecithin and proteins emulsify into an oil-in-water suspension — that is what makes the broth turn white, and frying also drives off much of the river-fish muddiness. Because dace is full of fine intermuscular bones, the fish is wrapped in muslin (鱼袋) or simmered loose and strained. The rice beans (赤小豆) are the slender 'rice bean,' chosen over the round red bean (红豆) for their stronger water-draining action in Chinese food-therapy, and adzuki-type beans hold their shape through hours of cooking. Long, steady simmering (老火) is what extracts collagen, amino acids and nucleotides for the soup's body and savor.
Variations
The fuller name 粉葛赤小豆鲮鱼汤 spells out the rice beans, which most cooks include; some add a few slices of pork or pork bones for a richer broth, and a small piece of dried tangerine peel (陈皮) is near-standard for cutting the fishiness. Cooks who want to skip the bone-picking buy ready-made fish bags or tie the dace in muslin; others fry it whole and serve the broth strained. In the same damp-clearing spirit, the kudzu is sometimes paired instead with red beans and pork in 粉葛猪骨汤, or carried into a sweeter register with the meatless 粉葛红豆汤.
On the Palate
Where Kudzu & Dace Soup sits in the Chinese flavor cloud
Ingredients
Serves 4How it's made
7 steps · 20 min
- 112 min
Peel the kudzu root and cut into large chunks. Rinse the rice beans and dried tangerine peel; soak the beans 30 minutes if time allows. Slice the ginger.
- 210 min
Scale and gut the dace, rinse and pat thoroughly dry. Heat oil in a pan and fry the fish over low-medium heat until golden on both sides; this browns the fish and cuts the muddy river smell.
Watch outFry the dace slow until both sides are firm and golden and the surface no longer sticks — that browned skin is what kills the muddy river smell and gives the soup its aroma.
- 33 min
If you want to avoid the fine bones, wrap the fried dace in a muslin fish bag (鱼袋); otherwise leave it loose to strain out later.
- 45 min
Bring a potful of water (about 2.5 litres) to a rolling boil, then add the kudzu, rice beans, tangerine peel, ginger and the fried dace all at once.
- 5150 min
Return to a hard boil, then lower to a steady gentle simmer and cook for about 2 hours, until the kudzu turns powdery and falls apart and the broth thickens and turns pale and milky.
Watch outKeep it at a steady low simmer for the full two hours — you're done when the kudzu crumbles at a poke and the broth has gone from thin and clear to pale and milky.
- 64 min
If the fish was left loose, lift it and the tangerine peel out (or strain the soup) so no fine bones remain.
- 71 min
Season with salt only and serve hot.
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