Heat the oil in a 10-inch cast-iron skillet over medium-high heat. Add the beef, onions, garlic and 1 teaspoon salt and cook, stirring and breaking up any clumps with a wooden spoon, until the meat is brown and the onions are softened, about 6 minutes. Add the tomato paste, chili powder and cumin and cook, stirring, about 1 minute. Stir in the enchilada sauce, beans, corn and cilantro and season with salt. Bring to a simmer. Remove from the heat and sprinkle with the cheese.
Add the cornmeal to a mixing bowl. Mix in the buttermilk and oil. You want the mixture to be thick but pourable. Stir in the scallions. Pour on top of the meat mixture in the skillet and spread in an even layer. Bake until the meat is bubbling and the cornbread is golden brown, 20 to 25 minutes.