‘Tom’ in Thai means to boil but when it`s used in relation to food dishes it means soup. ‘Yam’ means sour. Tom yum is usually made with prawns ( tom yum goong), Chicken ( tom yum kai), fish (tom yum pla), or mixed seafood (tom yum talay).Tom yum is always characterized by its distinct hot and sour flavors, with fragrant herbs generously used at the end of cooking.