1. Preheat the oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with nonstick spray or a little olive oil.

2. Heat the olive oil in a large skillet over medium-high heat. Add the ground beef and cook, breaking it apart with a spatula, for 5–7 minutes or until browned and no longer pink.

3. Stir in the diced onion and red bell pepper. Cook for 3–4 minutes, until the vegetables begin to soften. Add the minced garlic and cook for 30 seconds, just until fragrant.

4. Sprinkle the taco seasoning, ground cumin, salt, and black pepper over the meat mixture. Stir well so the spices coat the beef and vegetables evenly.

5. Pour in the diced tomatoes with green chiles (including their juices) and the tomato sauce. Stir to combine and bring the mixture to a gentle simmer for 3–4 minutes to let the flavors meld.

6. Add the black beans, frozen corn, and frozen peas to the skillet. Stir until the vegetables are evenly distributed in the sauce.

7. Fold in the cooked rice, mixing gently until it is fully coated in the saucy taco mixture. Taste and adjust seasoning with more salt or taco seasoning if desired.

8. Transfer the taco mixture to the prepared baking dish and spread it into an even layer. Sprinkle the shredded cheddar cheese evenly over the top.

9. Bake for 18–22 minutes, or until the cheese is melted, bubbly, and lightly golden around the edges. For a deeper color, broil for 1–2 minutes, watching closely.

10. Remove the casserole from the oven and let it rest for 5–10 minutes so it can set slightly and slice more neatly.

11. Top the casserole with chopped cilantro and diced avocado. Serve warm, adding a dollop of sour cream to each portion and any extra toppings you like such as salsa, jalapeños, or crushed tortilla chips.