Thua Dam Tom Kha (ถั่วดำต้มข่า)

An inventive vegetarian take on Thailand's beloved Tom Kha, this one-pot dish builds the classic lemongrass-galangal coconut broth around earthy black beans instead of the traditional chicken or seafood — a favourite in northern Thai vegan communities. The beans absorb the aromatic broth and become luxuriously creamy.

Serves: 4

Ingredients

• 300g (10.5 oz) dried black beans, soaked overnight and drained (or 2 × 400g cans, rinsed)
• 800ml (28 fl oz) vegetable stock
• 400ml (14 fl oz) can full-fat coconut milk
• 4 stalks lemongrass, lower third bruised and tied
• 6 slices fresh galangal (30g/1 oz)
• 6 kaffir lime leaves, torn
• 3 tbsp (45ml) fresh lime juice
• 2 tbsp (30ml) soy sauce
• 1 tbsp (15g) palm sugar
• 3 fresh bird's eye chillies, lightly crushed
• 200g (7 oz) oyster mushrooms, torn
• 3 spring onions, cut into 3cm lengths
• Large handful fresh coriander (cilantro)
• Steamed jasmine rice or sticky rice, to serve

Instructions

1. If using dried beans: cover with fresh water, bring to a boil, and simmer 50–60 minutes until just tender. Drain and set aside. For canned beans, skip this step.
2. In a large pot, combine vegetable stock, lemongrass, galangal, and kaffir lime leaves. Bring to a boil, then reduce heat and simmer 10 minutes to infuse aromatics.
3. Add coconut milk, bird's eye chillies, and cooked black beans. Simmer gently 10 minutes — the broth will turn a beautiful pale purple from the beans.
4. Add mushrooms and spring onions. Cook 3–4 minutes until mushrooms are just softened.
5. Season with lime juice, soy sauce, and palm sugar. Taste carefully — balance between sour, salty, and sweet is the hallmark of Tom Kha.
6. Remove lemongrass stalks. Ladle into bowls, top generously with fresh coriander, and serve with rice.

Cook's Notes: The galangal and lemongrass are flavouring agents, not meant to be eaten — warn guests. If you cannot source galangal, use a 50/50 mix of ginger and a dash of ground coriander. Black beans stain the broth; this is entirely correct and produces a dramatically beautiful purple soup.