For making Tom yum gai, which is another delicious variation of tom yum soup, you will have to use chicken and some other tasty spices. You can make tom yum soup in a number of ways. Examples are tom yum goong and tom yum nam khon; the former is made using shrimp and in the later, coconut milk is added to prepare the broth. However, if you think that just by adding chicken in place of shrimp, you can turn tom yum goong into tom yum gai, you are mistaken! Tom yum gai is quite different than other tom yum soups in terms of contents and way of preparation. You will have to purchase some ingredients used in this soup from a nearby Asian food shop. Soup made with fresh ingredients is best in taste, but dried ingredients can also be bought and stored, which will let you make the soup any time you want.
Following ingredients make soup for 4 people:
2 cups of chicken stock 2 tbsp of groundnut oil 2 stalks of fresh or dried lemongrass, chopped 3 slices of fresh galangal (2 slices are enough if dried one is taken) 2 tbsp of fish sauce 2 tablespoons of tamarind juice 3-4 kaffir lime leaves, can be taken either fresh or frozen 10 to 15 Thai chillies 2 green onions, sliced (optional) 1 medium onion, halved 5 slices of fresh ginger 2 to 3 tbsp of roasted chilli garlic sauce or chilli sauce 1 boneless skinless chicken breast half (half pound or 8 ounces, made into thin slices) 2 garlic flakes, chopped 2 tbsp of lime juice 4 to 5 ripe tomatoes, made into quarters (optional) 5 button mushrooms, made into quarters 10 small crimini or straw mushrooms, made into quarters Coriander (Cilantro) (to taste) 2 cups water
Heat the oil on a medium flame and saute in it the chicken, along with ginger and lemongrass in half the quantity and the onion. Keep on stir-frying till you see the chicken getting a bit pink and the onion getting transparent. Add the chicken stock with water and bring the mixture to a boil and add remaining lemongrass and ginger, fish sauce, galangal, kaffir lime leaves, and tamarind juice. You have to bring the mixture to a boil again and let it get cooked for 3 minutes. Now the chopped garlic flakes, cut mushrooms of both types and the chilli sauce is to be added. Reduce the heat and simmer the mixture for another 7 minutes. Now chillies and tomatoes are to be added. Reduce the fire to very low after some time and add the green onions and lime juice. You have to simmer the mixture for some minutes more. A more of fish sauce can be added as per your own taste. Turn off the heat. While serving a lot of cilantro leaves should be sprinkled on it and it should be served hot.
Keeping the chillies whole makes the soup mild, while chopping them makes the soup spicy. If dry chillies are used, you should decrease their quantity to 1/3rd that of the fresh ones, as they are spicier. Some people like tofu too, which can be added along with the chicken. These are to be cut into cubes and stir-fried, the same time when you stir-fry the chicken.