Preheat oven to 350℉
Cook rice according to directions or use leftover rice
Cut bell peppers in half lengthwise and remove the stems and seeds.
Heat oil in a cast iron skillet over medium heat or over the campfire. Add onions and cook until tender
Add ground beef and cook until no longer pink, about 5-7 minutes.
Stir in the cooked rice and season with taco seasoning, adding a splash of water if needed. Continue cooking for about 3-4 minutes.
Fill each pepper with the meat and rice mixture and arrange the peppers in the same cast iron skillet
Bake uncovered for 25-30 minutes or cover with foil and cook over campfire
Remove from oven and add cheese to top of peppers
Bake for 5 more minutes until cheese is melted
Serve with sour cream, avocado and salsa (optional)