Batter
1 cup rice flour
½ teaspoon ground turmeric
½ teaspoon kosher salt
Assembly
5 tablespoons (or more) vegetable oil, divided
4 oz. small shrimp, peeled, deveined
Kosher salt and freshly ground black pepper
6 scallions, thinly sliced
4 oz. mung bean sprouts (about 1 cup)
Large green-leaf or Bibb lettuce leaves and mixed tender herbs (such as mint, cilantro, and Thai basil; for serving)
Nuoc Cham (recipe below)