Som tam is a green papaya salad mostly associated with the northeastern part of Thailand (Isaan), though it is often suggested that it first appeared in Laos. Apart from thin strips of green papaya, this salad usually includes roasted peanuts, green beans, tomatoes, and a tangy sauce typically made with garlic, chili peppers, fish sauce, dried shrimps, palm sugar, and lime or tamarind juice.
The varieties are plentiful and can include various additions. The sauce can also appear in many other combinations, and can significantly vary in sweetness and spiciness. Numerous restaurants and street stalls allow the customers to choose the variety they prefer and adjust the ingredients to their preference.
It is still not clear whether this refreshing dish was invented in the north of Thailand, more precisely the Isaan region, or is it an original Lao creation. Many believe that it was primarily invented to utilize abundant papayas and that its original form did not use palm sugar because it mostly relied on spicy chili flavors.