Papaya Salad or Som-Tum in many style, e.g. Som-Tum Thai, Som-Tum Poo, Som-Tum Thai-Poo, Som-Tum Kung and a lot of other menu you can order with.
It's a traditional dish from North-East of Thailand (E-san). They're use to eat with sticky rice for their meal. All over the country, every where you go, you will fine most all the restaurants, food stall, even road side food stall, they all have this dish in their menu.
It's become a famous for Thai people and also foreigners to eat this dish every where. We use to eat with sticky rice and grill chicken.