Preheat the oven to 350°F and lightly grease a casserole dish.
Wash the bell peppers, slice a thin piece off the bottoms so they stand upright, then cut off the tops and remove seeds carefully.
Place the peppers upright in the casserole dish and bake for about 15 minutes until slightly softened.
In a large skillet over medium-high heat, cook the ground beef for about 5 minutes until browned.
Add the chopped onion and celery, and cook for 3 minutes until softened.
Stir in the garlic and cook for 30 seconds until fragrant.
Add the diced tomatoes, green chilis, cumin, chili powder, salt, and pepper. Stir to combine.
Add the black beans, corn, uncooked rice, and chicken broth. Mix well.
Cover the skillet and cook for 15–20 minutes, stirring occasionally, until the rice is fully cooked and tender.
Spoon the filling into the pre-baked peppers, packing it in and slightly mounding the tops.
Place a slice of provolone cheese over each stuffed pepper.
Bake for about 20 minutes, or until the cheese is melted and lightly golden.
Remove from the oven, garnish with fresh cilantro, and serve warm.
