Water. In Thailand, water is what everyone drinks with their Thai food. Sometimes a dark Thai beer as well, but water is what 95% of people drink.
Thai food is so spicy and flavorful that no other flavors need to be introduced with a beverage. I know in America everyone will want to drink a Coke or Dr Pepper (ha ha) with their Thai food, and I guess that’s okay.
But one of the allures of Thai food is that it is so healthy, which makes water a perfect pairing. I recommend you keep it simple, light, and healthy and stick with plain old H2O.
Undoubtedly, a significant reason why water is so popular in Thailand is the price factor. I don’t deny that, but I also suggest that water is perhaps simply the best pairing as well.
PS. If you’re looking for wine pairing suggestions for Thai food, you should hit the “back” button on your browser now :-). All wine in Thailand is imported from Europe and thus very expensive. No one drinks it here except for a minority of foreigners.