Preheat your oven to 350°F and lightly grease a 9x13 inch baking dish. While the oven heats, dice the yellow onion and green bell pepper into bite-sized pieces, mince the garlic, and cut the corn tortillas into 1-inch strips—this makes layering much easier than trying to fit whole tortillas in the dish. Rinse and drain the black beans to remove excess sodium and create a cleaner sauce. Have all ingredients measured and prepped within arm's reach before you start cooking the meat.

Heat a large skillet over medium-high heat and add the ground beef, breaking it apart as it cooks. Once the beef begins to brown, add the diced onion and green bell pepper, stirring occasionally until the vegetables soften and the beef is completely cooked through (about 8-10 minutes total). Drain off any excess fat using a colander or by carefully tilting the pan and spooning it out. I like to leave just a thin coating of fat in the pan—it adds flavor to the sauce without making the dish greasy.

Return the skillet to medium heat and add the minced garlic, cumin, and chili powder, stirring constantly for about 30 seconds until fragrant. Pour in the red enchilada sauce and add the rinsed black beans and corn, stirring well to combine. Bring the mixture to a boil, then reduce heat to medium-low and simmer for 10 minutes, stirring occasionally, to allow the flavors to meld. Taste and season with salt and pepper as needed. This simmering step is crucial—it lets the spices fully bloom and creates a more cohesive sauce rather than having ingredients floating separately.

Spread a thin layer of the meat sauce from Step 3 on the bottom of your prepared baking dish. Arrange 6 tortilla strips over the sauce to create the first layer, then spread half of the remaining meat sauce over the tortillas. Sprinkle half of the Mexican cheese (about 1.75 cups) over this layer. Repeat with another layer of 6 tortilla strips, then top with the remaining meat sauce. Reserve the remaining cheese for the final step—this two-stage cheese addition ensures you get a melted cheese layer throughout the casserole plus a nice golden top.

Place the casserole in your preheated 350°F oven and bake for 20 minutes until heated through and the edges begin to bubble. Remove from the oven and sprinkle the remaining 1.75 cups of Mexican cheese evenly over the top. Return to the oven and bake for an additional 5 minutes until the cheese is melted and lightly golden. Let the casserole rest for 5 minutes before serving—this allows the layers to set slightly and makes for cleaner portions.