Originally Posted by
GatoAndaluz
Pad thai in Thailand almost always uses tamarind paste for sweetness, whereas many renditions served in the US use sugar instead. Restaurants that use a more traditional recipe tend to have spice wheels on the tables, with three or four different condiments like in Thailand. Usually they are chile powder, fish sauce with diced bird's eye chile (nam plaa prik ki-noo), shrimp paste, and sugar.
Tamarind isn't sweet; it's sour.