Hot and sour prawn soup (Tom yam kung)

1. Peel the prawns, keeping the heads and shells; add them to the stock, simmer for 10 minutes and strain – this gives the soup real depth.

2. Cut the lemongrass into 4 cm pieces and bruise with the back of a knife, thinly slice the galangal, tear the lime leaves in half, crush the shallots and chillies, and quarter the mushrooms.

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

4. Add the mushrooms and cook for 2 minutes, then add the prawns and cook for just 1-2 minutes until pink.

5. Take off the heat and season with the fish sauce, lime juice and sugar – the soup should be sour, salty and hot all at once.

6. Sprinkle with coriander leaves and serve with rice; the lemongrass, galangal and lime leaves are not eaten.

Tip: Thailand's best-known soup; always add the lime juice off the heat, as it turns bitter when boiled. For a creamier version stir in 100 ml coconut milk at the end (the "nam khon" style).