1. Preheat oven to 375°F (190°C). Cut the tops off the bell peppers, remove seeds and membranes, and place them in a baking dish. Bake for 10 minutes to soften slightly.
2. In a skillet over medium heat, cook the ground beef until browned. Add onion, garlic, and taco seasoning, cooking until fragrant.
3. Stir in black beans, corn, diced tomatoes, and rice (if using). Simmer for 5 minutes, then season with salt and pepper.
4. Stuff each pepper with the beef mixture, pressing it down gently. Sprinkle shredded cheese on top.
5. Bake for 20 minutes, or until the cheese is melted and bubbly.
6. Serve warm, topped with sour cream, chopped cilantro, and a dash of smoked paprika if desired.