If you love Thai cookery this soup is sure to impress
It↑s essential that you use prawns with shells for this recipe, as the shells provide the flavour for the stock, shown here. We use ones with the heads removed but with the rest of the shell intact. If yours still have heads, you↑ll need to grip the body of the prawn in one hand and twist the head off with the other. For the rest of the shell, turn the prawn over and pull the shell open along the length of the belly, working from the head end downwards, prising it open so that you can pull the prawn free.
Once the shell is off, check to see if there is a black line running down the back of the prawn. This is the intestinal tract, or gut. If it's black, it's full. It's not harmful to eat, but the prawn looks better without it and it can be gritty. Removing it is called de-veining, as the gut looks like a vein. Using a small, sharp knife, make a shallow cut along the length of the black line, then lift it out using the tip of the knife.
Next take the shells left from the prawns and place into a thick-based pot and add the 420ml of cold water, the lime leaves and the outer husk of the lemon grass. Keep the soft centre aside for later. Bring to the boil and remove from the heat; strain and reserve the liquor.
Add the garlic, galangal or ginger, chopped centre of lemon grass and the shallot, and simmer for about 30 seconds. Next add the chopped chilli peppers and mushrooms and gently simmer for another 30 seconds.
Add the raw shelled prawns and again simmer for around 1-2 minutes or until the prawns are cooked. Finally, add the lime juice, spring onion and chopped coriander and finish with Thai fish sauce to taste (a few drops should be plenty). To serve, ladle carefully into warmed individual deep bowls, with a slice of lime on the side for those who like extra tang.
Fish Sauce can be tricky to track down - it's certainly worth the effort, but just to make things easier we stock it in our Cook Shop so you can pop in or order online.
125g shrimps/prawns (about 6), shelled and de-veined (see Critical Points), shells reserved for the stock
1 garlic clove, minced
2 dried kaffir lime leaves
a few thin slices fresh galangal or ginger
Thai fish sauce to taste
1 stalk of lemon grass (lower 1/3 of stalk, snap off the very hard part and freeze, to use as a base to bake fish)
1 shallot, finely sliced
25g straw mushrooms, sliced (if available)
1 red Bird↑s Eye chilli, or 1-2 green Thai chillies, finely chopped
25ml lime juice, freshly squeezed
handful of coriander, freshly chopped
2 spring onions, sliced at an angle