Shredded green papaya pounded with chilli, garlic, lime, fish sauce and palm sugar, with tomatoes, long beans and peanuts.
What makes it som tam
Green, unripe papaya.
Pounded, not tossed — in a clay mortar with a wooden pestle.
Sour, hot, salty and sweet at once.
Where it comes from
Som tam — 'sour pounded' — comes from Isan and Laos, where it's eaten with sticky rice and grilled chicken. The pounding bruises the papaya so it drinks in the dressing; the Lao version, with fermented fish, is funkier and sourer.