Prep the peppers: Preheat oven to 375°F (190°C). Lightly grease a baking dish.
Slice a thin layer off the base of each pepper if they wobble so they stand upright, being careful not to create holes.
Par-bake (optional but recommended): Place peppers cut-side up in the dish, cover loosely with foil, and bake for 10 minutes. This softens them slightly and shortens final cooking time.
Sauté aromatics: Heat olive oil in a large skillet over medium. Add onion and cook 3–4 minutes until softened.
Stir in garlic and cook 30 seconds until fragrant.
Cook the protein: Add ground turkey or chicken. Break it up with a spoon and cook until browned and no longer pink, about 5–7 minutes. If using black beans, skip browning and add them in the next step.
Season and build flavor: Stir in chili powder, cumin, smoked paprika, oregano, salt, pepper, and red pepper flakes if using.
Cook 30–60 seconds to bloom spices.
Add tomatoes and bulk: Mix in tomato paste, drained diced tomatoes, cooked brown rice or cauliflower rice, and corn if using. Simmer 2–3 minutes to combine and thicken. Taste and adjust salt and heat.
Stuff the peppers: Spoon the filling into each pepper, packing it slightly.
Top with a little shredded cheese if you like.
Bake: Cover the dish with foil and bake 15 minutes. Uncover and bake another 10–15 minutes until peppers are tender and cheese (if used) is melted and bubbly.
Finish and serve: Let cool 5 minutes. Garnish with cilantro and serve with lime wedges.
For extra freshness, add a spoon of salsa or Greek yogurt on top.