Prawn & coconut noodle soup

1 Shell the prawns (leaving the tails on, if liked) and put the shells in a pan to make the stock. Cover with 1 litre cold water, bring to a simmer and cook for 30 minutes. While the shells are cooking, devein the prawns and rinse them carefully; cover and chill until needed.

2 Meanwhile, put the ginger, shallots and lemongrass in the small bowl of a food processor. Roughly chop 1½ chillies and add to the processor (reserve the rest). Whizz with 2 tbsp water to a rough paste. Heat the oil in a large, heavy-based pan then add the paste. Cook, stirring regularly, for 5-7 minutes until fragrant. Add the fish sauce, tamarind and coconut milk to the pan and simmer gently.

3 When the shell stock is ready, strain and then discard the shells. Add the liquid to the coconut milk pan; bring back to a simmer. Cook the noodles according to pack instructions. Drain and rinse in cold water, then divide between bowls. Add the prawns to the soup and cook for 3-4 minutes until fully pink and cooked through. Ladle the soup over the noodles, slice the reserved chilli and scatter over the soup along with the Thai basil leaves.