Smoky sour fish soup with roasted shallots and chilli (Tom khlong)

1. Roast the shallots in their skins in a dry frying pan or directly over the flame for 6-8 minutes, turning, until soft and blackened in places; toast the dried chillies for 1 minute.

2. Peel and halve the shallots; cut the lemongrass into pieces and bruise it, slice the galangal and tear the lime leaves in half.

3. Bring the stock to the boil, add the roasted shallots, chillies, lemongrass, galangal and lime leaves and simmer for 5 minutes.

4. Stir in the tamarind paste, fish sauce and palm sugar, then add the fish fillet in large pieces and simmer gently for 5 minutes.

5. Take off the heat and sharpen with lime juice.

6. Sprinkle with coriander and serve with rice.

Tip: The central Thai "canal" soup: traditionally made with smoked or dried fish, with roasted shallots and chilli giving it smoky depth. If you can find smoked mackerel, use it for half the fish fillet.