Adjust oven rack to middle position and heat oven to 450 degrees.
Cook thinly sliced whites of 4 scallions in 1 tablespoon vegetable oil in 12-inch nonstick skillet over medium-high heat until sizzling, about 1 minute.
Stir in 1 tablespoon tomato paste, 1 tablespoon chili powder, and 1 teaspoon cumin and cook until fragrant, about 1 minute.
Stir in 14 ounces shredded extra-firm tofu, 1 rinsed can black beans, and 1 teaspoon table salt and cook until liquid evaporates and tofu begins to brown, 4 to 6 minutes.
Brush both sides of 12 corn tortillas with remaining 2 tablespoons oil.
Spread ½ cup enchilada sauce over bottom of 13 by 9-inch baking dish, then arrange half of tortillas over sauce.
Spread tofu mixture evenly over tortillas, then top with ½ cup enchilada sauce and 1 cup shredded Monterey Jack.
Arrange remaining tortillas on top, followed by remaining ½ cup enchilada sauce and 1 cup shredded Monterey Jack.
Bake until hot throughout and cheese is melted, 8 to 12 minutes.
Sprinkle with thinly sliced greens of 4 scallions and serve.
