09/03/2023
Various aromatic ingredients are sliced, roughly pounded, and simmered to extract their flavor. These include fresh ingredients such as lemongrass, kaffir lime leaves, galangal, chilis, shallots, and garlic. For shrimp-based soups, shrimp shells and heads may also be simmered, to extract their flavor. These ingredients are often then removed as their flavor is now extracted and many aren't edible. However they may be left in, as an aid to presentation.[5]
Alternatively, commercial tom yum paste may be used. This is made by crushing all the herb ingredients and stir frying in oil, then adding seasoning and other preservative ingredients. The paste is bottled or packaged and sold around the world.
Vegetables are then added, such as onion and tomato. In modern popular versions the soup may also contain mushrooms—usually straw mushrooms or oyster mushrooms.[5]
Various meats are added next, commonly fish, shrimp, mixed seafood, pork, or chicken.[5]
When the meat is cooked, final flavorings whose taste is destroyed by heat, such as fish sauce and lime juice, are added. For most varieties a paste called nam phrik phao (Thai: น้ำพริกเผา) is also added, made from shrimp, chilis, shallots, and garlic.[6] This imparts sweet, salty, and spicy tastes.[5]
