Tom Yum Soup with Prawns

Ingredients

• 400 g raw prawns, peeled, shells kept
• 1.2 litres chicken stock
• 2 lemongrass stalks, bruised and cut into lengths
• 25 g galangal, sliced
• 5 kaffir lime leaves, torn
• 3 bird's eye chillies, bruised
• 200 g mushrooms, halved
• 150 g cherry tomatoes, halved
• 3 tbsp fish sauce
• juice of 3 limes
• a handful of coriander

Method

1. Use the shells

   Fry the prawn shells in a dry pan until they turn orange and smell sweet, then add the stock and simmer for 10 minutes and strain. Throwing the shells away wastes the best flavour in the dish.

   10 min

2. Infuse the aromatics

   Return the stock to the pan with the lemongrass, galangal, lime leaves and chillies and simmer gently. These are for flavour, not eating — leave them in large pieces so they are easy to avoid at the table.

   10 min

3. Mushrooms and tomatoes

   Add the mushrooms and tomatoes and cook until the tomatoes are just beginning to slump.

   5 min

4. Prawns last

   Slide in the prawns and take the pan off the heat as soon as they turn opaque, about 2 minutes. The residual heat finishes them.

   2 min

5. Balance off the heat

   Add the fish sauce and lime juice away from the heat and taste — it should be sharply sour first, then salty, then hot. Boiled, lime juice turns bitter, which is why it never goes in early.