In a large skillet over medium heat, add the ground beef and diced onion. Cook until the beef is browned and the onion is translucent, about 5-7 minutes. Drain any excess fat.

Stir in the minced garlic, chili powder, cumin, salt, and pepper. Cook for an additional 1-2 minutes until the garlic is fragrant.

Add the enchilada sauce, black beans, corn, and cooked rice (if using) to the skillet. Stir everything together until well combined. Allow the mixture to simmer for about 5-10 minutes, stirring occasionally.

Once heated through, sprinkle the shredded cheese over the top. Cover the skillet with a lid and let it sit for about 2-3 minutes, or until the cheese is melted.

Remove from heat and garnish with fresh cilantro. Serve hot with optional toppings like sour cream or sliced avocado.