There are many different soups found in Thailand, made with all types of seafood, poultry and meats. The one thing they all have in common is that intriguing flavor that is simultaneously sour, salty and spicy. Thais call this flavor Yum. Yum is perhaps the most important flavor in Thai cooking. You may recognize the word "Yum" in Thai dishes like Yum Nuea (spicy beef salad) and of course tom yum soup.
The ingredients that give us this magical combination are the basics of the Thai kitchen. Salt is rarely used; instead there is fish sauce (nam pla), a liquid made from salted fermented fish. It doesn't sound very appetizing, but it is indispensable in Thai cooking.