Spicy and ear-tinglingly sour, this classic Thai soup is just what I fancy at this time of year: it’s something to cut through the pleasant, festive fug and reset the senses. Though shellfish are a common ingredient, this soup is almost endlessly adaptable, even for vegans: as long as it vibrates with flavour – aromatic lime leaves and lemongrass, warming galangal and fresh citrus – you’re on the right track.
Prep 12 min
Cook 15 min
16 raw shell-on king prawns
1 dash vegetable oil
4 fresh makrut lime leaves
2 lemongrass stalks
2 thick slices galangal
2 bird’s eyes chillies
1 tbsp palm sugar, or soft brown sugar
Juice of 1½ limes
2 tbsp fish sauce
1 handful coriander or Thai basil leaves, to serve
1 A note on the prawns
You’ll need raw, shell-on prawns here. Frozen are fine, so long as they’re defrosted and soft enough to shell, but if your prawns are very large (or very small), adjust the quantities accordingly. If you can find only shelled prawns, use a litre of light fish or chicken stock (or even just water), and start from step 3.
2 Make a stock with the prawn shells
Shell the prawns, retaining the shells and heads, and set aside the meat for the time being. Heat the oil in a frying pan over a medium-high flame, then fry the shells and heads, stirring regularly, until they turn a vivid pink.
Add a litre of water, bring up to a lively simmer, then strain into a clean pan and discard the spent shells.
3 Prepare the aromatics
Roughly tear the lime leaves (avoid using the dried kind here: frozen are fine, though, but fresh are infinitely preferable and fairly widely available). Bruise the lemongrass by pressing down on it with the flat of a large knife, then cut it into roughly 5cm lengths.
Cut two thick slices of galangal – this ginger-like root is sold in specialist south-east Asian food stores and some large supermarkets, but use ginger if you can’t source any.
4 Infuse the stock
Add the lime leaves, lemongrass and galangal to the stock pan, bring it back up to a simmer, then leave to bubble gently and infuse for five minutes. Meanwhile, finely slice the chillies, leaving the pith and seeds inside (depending on your taste for spice, add more, if you like). Slide the chillies into the broth and leave the stock to blip away for a couple of minutes longer.
5 Add the prawns
Turn down the heat to the barest simmer, add the prawn meat to the broth and cook for about a minute, until just pink (be careful not to let the stock boil or to cook the prawns for too long, or they will turn rubbery).
Take off the hob, stir in the sugar, lime juice and fish sauce, then taste and adjust the seasoning as necessary.
6 Serve with lots of fresh herbs
Ladle the soup into bowls, making sure the prawns are evenly divided, then tear in the fresh herbs in generous quantities and serve immediately.
It’s not traditional, but you can bulk out the soup by adding some cooked rice noodles if you want to make it a more substantial dish, or add other vegetables such as chopped tomatoes, mushrooms or whatever else takes your fancy.
7 Alternatives to shellfish
If you’re not a shellfish fan, make this with good chicken stock, and add torn cooked chicken (or pork or turkey) at the end, just to warm it through. There’s also a more modern, richer variation of tom yum in which coconut or evaporated milk is added at the end of cooking: if that appeals, make only 750ml stock, and stir in 300ml coconut milk with the seasonings just before serving.
8 … or to veganise
To make this vegan, use vegetable stock or water, and add two round shallots, peeled and cut into wedges, along with the aromatics in step 3. Add two deseeded and roughly chopped tomatoes and 200g chopped oyster, shiitake and/or chestnut mushrooms with the chillies. Vegan versions of fish sauce are available, and I’d recommend getting hold of some for this dish.
9 Other flavourings
Vegan or not, you can also add some firm diced tofu instead of the prawns; I think it’s also rather nice with those fried tofu puffs sold in specialist south-east Asian food shops. Pick up a jar of we fell while you’re there: this rich, sweet chilli paste, also available in vegetarian form, is a great addition to tom yum, and a great many other dishes besides.