Supanniga Eating Room runs on Thai grandma love, specifically Grandma Somsri Jantra's, pulling recipes from her Trat and Khon Kaen roots. There are three locations across Bangkok now, but the Tha Tien spot lets you sit on the Chao Phraya, directly facing Wat Arun.
Eastern and northeastern Thailand is on the menu. Try moo chamuang: fatty pork gone tender under chamuang leaves, with that mineral bite that's almost medicinal. Namprik khai pu loads fat crab and roe with vegetables, carrying real heat. Kalumpli tord nampla is cabbage fried in Trat fish sauce until it caramelises, teetering on too salty until rice pulls it back.
One dessert here doesn't show up at the other locations: coconut rice cake with taro, corn and dried shrimp. They make it in limited batches daily, so call ahead or you're out of luck.