Tom yum: a soup seasoned only after it leaves the heat
Tom yum is hot, but above all it is sour — and that acidity is its most fragile element. Lime juice boiled with the soup loses its fresh citrus aroma and leaves only sourness. Which is why the lime — and, in this recipe, the fish sauce too — goes in after the pot comes off the heat, at the very end. The second rule concerns lemongrass: the stalks are bruised and added in pieces, then fished out before serving — they are inedible.
Your own work in that: 33 min.
- Broth 20 min
- Vegetables 8 min
- Seasoning 5 min
Step by step
0 / 6 doneBruise the lemongrass
Trim the woody ends from the lemongrass stalks, bruise them along their length with the flat of a knife and cut into 5 cm lengths. Bruising ruptures the fibres and releases oils; a whole stalk would give up far less of them to the broth.
Ingredients: 1200 ml chicken stock · 3 pcs lemongrass · 40 g fresh ginger or galangal · 1 pcs lime zest · 3 pcs red chillies
TipLemongrass <b>is not eaten</b> — it is tough and fibrous. It goes in as large pieces precisely so that it can be fished out easily before serving.
Bruised with a knife, cut into 5 cm lengthsInfuse the aromatic broth
Bring the stock to the boil and add the lemongrass, ginger, strips of lime zest and bruised chillies. Simmer 15 minutes, covered. The broth should smell intensely citrus — that is the foundation of this soup.
Fifteen minutes, until it smells of citrusAdd the vegetables
Add the mushrooms, tomato quarters and sliced onion. Simmer 5 minutes. The mushrooms should soften but the tomatoes must not collapse — everything in tom yum stays in distinct pieces; it is not a smooth soup.
Ingredients: 400 g prawns · 250 g mushrooms · 2 pcs tomatoes · ½ pcs red onion
Add the prawns for two minutes
Add the peeled prawns and cook exactly 2 minutes, until pink and curled into a C. Take the pot off the heat immediately — the prawns finish cooking in the hot broth. Overcooked prawns turn rubbery and there is no fixing that.
Two minutes, curled into a CSeason off the heat
With the pot off the heat, fish out the lemongrass, ginger and zest. Add the fish sauce, the juice of three limes and the sugar. Taste and adjust — it should be very sour, clearly salty and hot, in that order of importance.
Ingredients: 4 tbsp fish sauce · 3 pcs limes, juice · 2 tsp brown sugar · 1 bunch fresh coriander · 100 ml coconut milk
TipBoiled lime juice loses the volatile compounds responsible for its fresh citrus smell, leaving only sourness. This is the point in the recipe where order matters most.
Lime and fish sauce off the heatServe with coriander
Ladle into bowls and scatter with a whole bunch of chopped coriander. For the creamy version (tom yum nam khon), stir in the coconut milk with the lime. Serve at once, while the prawns are still tender.
A whole bunch of coriander, straight to the table
Before you start
Prawn shell stock
Fry prawn shells and heads in oil 3 minutes, cover with a litre of water and simmer 20 minutes. It makes an excellent broth for this soup, and the cheapest — made from what usually goes in the bin. Use it in place of the chicken stock.
What galangal is
Galangal is a relative of ginger with a resinous, citrus-and-pine aroma and less heat — in Thailand it is a staple of tom yum. Ginger is an easy-to-find substitute but gives the soup a different, sharper character.
Without fresh aromatics
Lemongrass and kaffir leaves freeze well — buy a supply at an Asian shop and keep it in the freezer. Dried versions are much weaker: most of their aroma is in volatile oils, and much of it escapes during drying.
Heat level
Three bruised chillies give a clearly hot soup. In Thailand many cooks use far more. Bruising rather than chopping makes them easy to remove and lets you control how long they release capsaicin.
