Tom yam (or tom yum), apotheosis of Thai food, darling of central Thai cuisine, is a complex and delicious soup. In spite of its exoticism, however, it is surprisingly easy to prepare, provided you can find the unusual ingredients required to make it. Don't settle for tom yam soup powder, or paste, in bottles or packages, if at all possible. Seek out fresh aromatics and make it from scratch.
Tom yam, perhaps sold as spicy sour soup or some such at Thai restaurants, comes in many varieties - shrimp and mixed seafood being the most common in Thailand itself, with chicken and vegetarian versions lagging not far behind. I've tried to cover all those versions here.
What you'll need
- 8 cups (2 litres) broth - chicken stock, fish stock*, lemongrass broth, or water if you must
- 3 or 4 stalks of lemongrass, tough outer layers removed, cut into 2 inch sections and whacked once or twice smartly with a chef's knife or pestle
- 6 or 8 lime leaves, torn into 2 or 3 pieces
- a chunk of galangal, unpeeled, sliced into 7 or 8 pieces the size of a large coin
- 3 or 4 roots, with perhaps half an inch of stem attached, from sprigs of coriander (cilantro), well washed; reserve the leaves for garnish
- 2 tblsp (30 ml) fish sauce (nam pla), or 2 tblsp (30 ml) Golden Mountain Sauce or 2 tsp (10 ml) salt for vegetarians
- 1 tsp (5 ml) palm sugar or brown sugar
- 1/2 lb (225 gr) oyster mushrooms, straw mushrooms, or button mushrooms, sliced
- 1/2 lb (225 gr) tiger shrimp (shelled and deveined), or mixed seafood (fish chunks, squid rings, clams etc), or chicken breast cut into bite-sized chunks (hint: choose one, not all three options)
- 2 roma (plum) tomatoes, sliced into thin wedges
- 3 or more hot Thai chilis
- 1 tblsp nam prik phao or chili jam
- 2 scallions, chopped, for garnish
What to do
Let's begin with the base flavours in this soup. You know and I know that homemade stock will give the best results, but I reluctantly admit that here, plain water will do in a pinch, because part of what makes this soup so special is the aromatics - lemongrass, galangal, lime leaves, coriander roots. They are here for their amazing aroma and flavour, but are not meant to be eaten. Thai people know this, so they just push these various sticks and leaves to the side of their bowls when they encounter them in their soup. If it bothers you to have these largely inedible chunks in your soup, put them in a cloth bag or piece of cheesecloth so they won't be floating about in the finished product. Okay then. Bring the stock to a boil in a heavy-bottomed pot and add the aromatics, free or bound in a bag. Then turn the heat down and simmer (don't boil) for 10 minutes or so to bring out their flavour. Leave the pot uncovered so some of the water evaporates. Things should start smelling really great.
Now add the fish sauce, palm sugar, mushrooms, and chicken if you're using it. Cook for about 2 or 3 minutes, till the mushrooms start to soften.
Add tomatoes and shrimp or seafood, if using, and simmer just till it's cooked. It should take only a minute or two.
Okay, you're getting close now. Stir in the lime juice and nam prik phao. Whack the chilis once or twice with a chef's knife or pestle to release their oils, and plunge them into the soup. I recommend leaving them in for up to 1 minute and then removing them; it will only take one eaten by mistake to convince you that this removal is a good idea. These babies are hot. Also, if you've put your aromatics in a bag, remove them too. Garnish the soup with chopped coriander and scallion and eat.
In Thailand this soup comes to your table in a large doughnut-shaped pot with a flame burning underneath; the intent is to keep the soup warm as you proceed through your meal. But who has such a thing here? I just serve the soup in a large bowl, and give each diner a small bowl and one of those flat-bottomed Chinese soup spoons and ladle a little out for each person, explaining about the twigs and leaves you're not supposed to eat.
This soup is not a separate course, but one of the many dishes that grace the Thai dinner table, to be eaten with jasmine rice and a host of other wonderful dishes like a coconut milk curry, a stir fry or two, and other amazing delicacies that are everyday fare in that lovely kingdom.
*To make an easy shrimp stock, just keep the shells from your shrimp (assuming you bought them with shells on, as I always do, for they're much cheaper), add them to the water you will use for your soup, bring to the boil, and simmer for about 10 minutes. Voila!