Guizhou Kaili Sour Soup (Kaili Suan Tang) Tradition

Ingredients

• For the sui bing (fermented starter)
• 1.5 litres rice washing water, collected from the second or third rinse of raw rice
• 200 g ripe tomatoes, roughly chopped, added to the fermenting water
• 3–4 fresh red chilies, split lengthways
• For the soup
• 600 g grass carp, cleaned and cut into bone-in steaks approximately 3 cm thick
• 800 ml fermented sui bing starter, strained from the earthen jar after 5–7 days
• 150 g fresh tomatoes, sliced, added alongside ferment for layered tomato character
• 100 g fern shoots, trimmed; or substitute watercress
• 80 g watercress, washed, large stems removed
• 1 tsp litsea cubeba (mu jiang zi), whole berries or lightly crushed — Miao aromatic
• 10 g salt, to taste

Method

1. 1
   Pour the rice washing water into a clean earthen jar. Add the roughly chopped tomatoes and split chilies. Cover loosely with cloth and leave at stable room temperature for 5 to 7 days. The sui bing is ready when the liquid smells cleanly sour — sharp and lactic rather than putrid — and the surface shows fine, even bubbling.
2. 2
   Strain 800 ml of the fermented starter into a pot. Add the fresh tomato slices. Bring to a gentle simmer over medium heat and cook for 8 minutes, pressing the tomatoes lightly against the side of the pot to release their juices. The broth deepens to a brick-orange and the raw edge of the ferment rounds into a full, layered sourness — taste to confirm.
3. 3
   Add the litsea cubeba berries to the simmering broth. Season with salt. Stir once and allow the berries to infuse for 2 minutes — the broth will carry a faint citrus-pepper fragrance.
4. 4
   Slide the grass carp steaks into the broth. Maintain a gentle simmer — do not allow a rolling boil. Cook for 4 to 6 minutes only. The fish is done when the flesh at the bone turns from translucent to opaque white and yields slightly to a chopstick without flaking away entirely; overcooking toughens the protein and destroys the clean sweetness of the fish.
5. 5
   Add the fern shoots and watercress. Cook for no more than 90 seconds — the greens should retain their colour and a slight resistance to the bite, providing herbal freshness that balances the acidity of the broth.
6. 6
   Ladle into deep bowls, distributing fish, greens and broth evenly. Serve immediately.