Prepare the beef filling: In a large skillet over medium heat, brown ground beef. Drain off excess grease. Add onion and garlic and cook until softened. Stir in chili powder, cumin, oregano, salt, and pepper.

Combine the sauce: In a separate bowl, combine tomato sauce, diced tomatoes and green chilies, and refried beans.

Assemble the enchiladas: Preheat oven to 375°F (190°C). In a greased 9x13 inch baking dish, spread a thin layer of the sauce.

Fill the tortillas: Dip each tortilla in the remaining sauce, then fill with a portion of the beef mixture and cheese. Roll up the tortilla and place seam-side down in the baking dish.

Top and bake: Pour the remaining sauce over the enchiladas and top with shredded Monterey Jack and Cheddar cheese. Bake for 20-25 minutes, or until the cheese is melted and bubbly.

Serve: Let the enchiladas cool for a few minutes before serving.

Optional additions:

For a spicier enchilada: Add a tablespoon of hot sauce or a pinch of cayenne pepper to the beef filling or sauce.

For a vegetarian option: Replace the ground beef with a plant-based protein, such as crumbled tofu or tempeh.

For a healthier twist: Use whole-wheat tortillas and top with fresh avocado slices.

Enjoy your delicious beef enchiladas!