Heat 1 tablespoon of the oil in a small pot over medium heat. Add the scallion whites and cook, stirring, until softened, 1 to 2 minutes.
Add the beans, ¼ cup water, and ½ teaspoon each salt and pepper. Cook until warmed through, 3 to 4 minutes. Stir in the scallion greens.
Toss the shrimp with the egg white in a shallow bowl,. In a separate shallow bowl, combine the flour, cornmeal, ½ teaspoon salt, and ¼ teaspoon pepper. Add the shrimp and toss to coat.
Heat the remaining ½ cup of oil in a large skillet over medium-high heat. Fry the shrimp, in batches, until golden, 2 to 3 minutes per side.
Serve the shrimp in the tortillas with the avocado, salsa, cilantro, hot sauce, sour cream, and lime wedges, alongside the beans.