Two of Nik’s favourite words in the kitchen are ‘zingy’ and ‘zesty’, and this is one recipe they can definitely be applied to. It’s a hot, fragrant, sweet-sour soup that is remarkably flavoursome. Although it seems quite simple, there it is a form of alchemy towards the end; the flavours only come together at the last minute when you add the nam pla (fish sauce), lime juice and palm sugar. Take down the amount of chillies a little if you don’t like your sinuses to be cleared, but do try to leave some in. The mushrooms add a bit of extra texture and flavour, but are optional. We’ve got into the habit of freezing the raw prawn heads and shells from other recipes that use peeled raw prawns (prawn gyoza, for instance), so chuck these in if you have them too, as they add to the flavour of the stock

16 raw shell-on king prawns

4 prawn heads and shells defrosted (see above – optional)

dash of groundnut oil

4 button mushrooms, finely sliced (optional)

250ml fish stock or veg nage

500ml vegetable nage

6 kaffir lime leaves, roughly torn

3 lemongrass stalks, very finely chopped

4 slices of galangal

4 bird’s eye chillis, very finely chopped

2 tbsp nam pla (Thai fish sauce)

1 tbsp palm sugar

Juice of 1½ limes

Handful of coriander and Thai basil leaves.

Prawn crackers to serve

• Shell the prawns, and set the meat aside. Heat the oil in a large saucepan over a medium heat and fry the prawn heads and shells until pink. Add the chicken stock, vegetable nage, and 500ml water; and bring to the boil. Simmer for 8 minutes

• Strain and discard the shells. Return the prawn stock to the pan, add the lime leaves, lemongrass, and galangal. Bring back to the boil and leave to infuse for five minutes, then add the chillis and simmer for a further two minutes

• Add the prawns and mushrooms, and cook through until the prawns turn pink. Take off the heat. Add the nam pla, half of the palm sugar, and the lime juice. Check for flavour, add more palm sugar (or lime) according to taste. Garnish with coriander and basil, and serve with prawn crackers