I’ve written about som tam a few times before. It’s usually made with papaya, but it can be made with other stuff. Here is green mango som tam. It’s made with green mango, peanuts, chilies, cilantro, shallots, fish sauce, lime juice, and some tiny whole black crabs:
As with so much other street food in Thailand, showmanship is everything when the street vendor prepares your food, and this guy did not disappoint (I also suspect he’s probably quite the ladies’ man).