This is one of those approximate recipes that all cooks have in their heads. You can use either green or red (or orange or yellow) peppers.
Slice off the tops of the peppers, set the bottoms aside, and chop the tops, discarding the stems.
Pan fry the chopped pepper with chopped onion and ground beef. Season with salt and pepper and oregano; add a little tomato sauce.
Add some cooked rice.
Place the bottoms of the peppers in a greased casserole dish, fill with the stuffing and put the rest of the stuffing over the top of everything. I always make too much stuffing, so my individually stuffed peppers always morph into a kind of casserole.
Sprinkle with grated cheese, then with Italian bread crumbs, then with Parmesan cheese.
Bake covered at 350 for around 45 minutes, then remove the cover and bake for an additional 10 minutes to crisp the top.