Mae Sariang is small but eats well, with a strong northern Thai accent and a few Shan and Karen touches you do not get further east. Most of the visitor-facing places are along the river road; the locals' canteens are clustered behind the market.
Look for khao soi, the rich coconut-curry noodle soup; nam ngiao, the northern tomato-and-pork rib broth; and sai ua, the lemongrass-and-galangal sausage from the morning market. Several of the riverside guesthouses do reliable Thai-Western menus on shaded terraces. For the genuine article, eat at the morning market or in the small noodle shops along Mae Sariang's main road.