Prep the peppers. Preheat your oven to 375°F (190°C). Slice the tops off the bell peppers and remove seeds and membranes.
If needed, shave a thin slice from the base so they stand upright. Place in a baking dish, cut side up.
Soften the peppers (optional). For softer peppers, brush with a little olive oil and bake for 10 minutes while you make the filling. For crisper peppers, skip this step.
Cook the aromatics. Heat olive oil in a large skillet over medium heat.
Add diced onion and cook 3–4 minutes until softened. Stir in garlic and cook 30 seconds until fragrant.
Brown the meat. Add ground meat to the skillet. Cook, breaking it up, until no longer pink.
Drain excess fat if needed.
Season and simmer. Stir in taco seasoning, tomato sauce or salsa, beans, corn, and cooked rice. Add a splash of water if it looks dry. Simmer 2–3 minutes.
Taste and adjust salt and pepper.
Stir in some cheese. Mix in a small handful of shredded cheese so the filling holds together. Save most of the cheese for topping.
Stuff the peppers. Spoon the filling into each pepper, packing it gently to the top. Sprinkle generously with the remaining cheese.
Bake. Cover the dish loosely with foil and bake for 20 minutes.
Remove the foil and bake another 10–15 minutes, until the peppers are tender and the cheese is bubbly and golden.
Finish and serve. Let cool for 5 minutes. Top with cilantro, a squeeze of lime, and your favorite toppings. Serve warm.