Tom yum prawns

Of the four dishes here, this is the one where head on, shell on shrimp make the biggest difference. The shells and heads become the stock, and the tomalley in the heads gives the broth its colour and its depth. Buying peeled shrimp for tom yum means discarding the best ingredient before you start.

This is the creamy nam khon style built on chilli jam, which is the version most people recognise from restaurants. A clear version is covered in the notes.

Shrimp stock

• Shells and heads from 500 g PhycoNor red legged shrimp
• 1 tbsp neutral oil
• 1 litre water
• Optional: 1/4 cup chopped onion

Soup

• The peeled shrimp from above, tails on or off
• 2 stalks lemongrass, bottom half only, bruised and cut into 5 cm pieces
• 8 thin slices galangal
• 6 makrut lime leaves, torn, centre rib removed
• 2 to 5 Thai birds eye chillies, pounded or finely chopped
• 200 g oyster or straw mushrooms, torn into bite size pieces
• 1 medium tomato, cut into wedges
• 3 to 4 tbsp nam prik pao, Thai chilli jam in oil
• 3 tbsp fish sauce
• 1/2 cup fresh lime juice, about 4 limes
• 1 tsp sugar, only if needed
• 1/4 cup evaporated milk, optional
• Coriander, chopped, to garnish

1. Peel and keep everything. Peel the shrimp, leaving the tails on if you like, and put every shell and head into a pot. Devein the shrimp and set them aside.
2. Make the stock. Add the oil to the pot with the shells and heads over medium high heat. Fry for 3 to 4 minutes, pressing the heads with a spatula to squeeze out the tomalley, until the shells are orange and the base of the pot begins to brown. Pour in the water, scrape the bottom, bring to a simmer and cook for 10 minutes. Strain and discard the shells. You want about 900 ml of stock, topped up with water if short.
3. Infuse the herbs. Return the stock to the pot and add the lemongrass, galangal, lime leaves, chillies and mushrooms. Simmer for 5 minutes.
4. Season. Bring to a rolling boil. Loosen the chilli jam with a ladle of hot stock, then stir it in along with the fish sauce and tomato.
5. Cook the shrimp. Drop in the shrimp and cook for 30 to 45 seconds, then turn off the heat and let the residual heat finish them over about a minute. This keeps them tender.
6. Finish off the heat. Stir in the lime juice, and the evaporated milk if using. It should lead with sour, then salt and heat, with just enough sweetness to round it off. Add fish sauce if it tastes flat, sugar only if it tastes too sharp.
7. Garnish with coriander and serve with jasmine rice. Tell people the lemongrass, galangal and lime leaves are there for flavour rather than for eating.

• Nam prik pao, the chilli jam, is not the same product as instant tom yum paste.
• Lime juice always goes in off the heat. Boiling it turns it bitter.
• For a clear broth, leave out the chilli jam and evaporated milk and add a teaspoon of sugar instead.
• Galangal and ginger are not interchangeable here.