Hot and sour prawn soup with young coconut (tom yum)

Instructions

1. Peel and devein the prawns, placing the heads and shells in a colander and setting aside the prawn meat. Rinse the heads and shells under cold running water and set aside.
2. In a large saucepan over medium heat, combine the stock and salt, stirring to dissolve the salt. Add the prawn heads and shells, bring to the boil and simmer for 10–15 minutes, until the red oil from the prawn heads begins to float on the surface. Remove from the heat and strain the liquid through a sieve into another large saucepan, pressing down on the heads and shells to extract as much flavour as possible. Discard the heads and shells.
3. In a mortar and pestle, bruise the chillies, lemongrass and galangal and place in the saucepan, along with the makrut lime leaves. Return the stock to the heat and bring to the boil.
4. Add the fish sauce and prawns and simmer, uncovered, until the prawns change colour. Quickly remove from the heat and add the lime juice.
5. Check the soup for seasoning; it should have a balance of salty, sour and spicy flavours. Adjust the seasoning with extra fish sauce, lime juice or bruised chillies if necessary.
6. Ladle the soup into bowls and garnish with the young coconut meat and coriander. Serve hot with steamed jasmine rice.