Som tam (Thai/Isan ส้มตำ) is a spicy papaya salad originating in Laos and the Isan region of northeastern Thailand. Som (ส้ม) in Isan and Lao is sour, and tam (ตำ) means pounded. The transliteration is also sometimes written as som tum, som dtam or som dtum. Other names for the dish are papaya pok pok (from the sound produced when preparing the dish in a mortar), tam som or, in Lao and Isan, tam mak hung (mak hung is the Lao and Isan word for papaya).
The main ingredient is grated, unripe papaya, seasoned and pounded to a softened state in a mortar. Chili, garlic, lime and fish sauce are also usually added, while yardlong beans and tomato are optional. There are many variations of the dish, some made with carrot instead of papaya. The dish combines the four main tastes of Lao/Thai cuisine: sour lime, hot chilli, salty fish sauce, and sweetness added by palm sugar. The papaya itself is unripe and fairly neutral tasting.