In a large skillet, heat over medium heat. Add in the ground beef and finely diced onion. Cook for about 5-7 minutes, stirring frequently, until the beef is fully browned and the onions are tender and translucent. Drain excess fat if necessary.
Incorporate the minced garlic into the skillet and sauté for about 1 minute.
Sprinkle the taco seasoning over the beef mixture, then add the rinsed black beans, drained corn, and the can of diced tomatoes with green chilies. Mix thoroughly and let it cook for an additional 2-3 minutes.
In a large mixing bowl, combine the cooked rice with the seasoned beef mixture. Fold in 1.5 cups of shredded cheddar cheese and the sour cream, mixing gently. Season with salt and freshly cracked black pepper to taste.
Grease a 9x13 inch casserole dish. Pour the beef and rice mixture into the dish, spreading it out evenly.
Sprinkle the remaining 0.5 cup of shredded cheddar cheese over the top. Add a layer of crushed tortilla chips over the cheese.
Place the dish in the preheated oven and bake for 25-30 minutes, or until the cheese is melted, bubbly, and slightly golden.
Once baked, remove from the oven and let it sit for 5 minutes.
Just before serving, sprinkle fresh cilantro over the top.
Notes
Serve warm with additional tortilla chips and salsa or guacamole.