Tom Yum is likely the most famous of all Thai soups in Thai restaurants (and kitchens) worldwide. It is a clear, spicy and sour soup with a variety of fragrant Thai spices including lemon grass, galangal root and kaffir lime leaf. There are vairiety of Tom Yum with selection of shrimp, fish, seafood, chicken or mushrooms. However, The most well-known Tom Yum is Tom Yum Koong made of shrimp (in Thai, "Koong" or "kung"). For more excitement, Tom Yum can be served simmering with seafood in a traditional "frame shooting hot pot".
The original Tom Yum is very hot, sour and spicy and always goes well with steamed rice. Many people have mistaken it by its distorted milder-than-original taste and by being served (outside of Thailand) as an appetizer.