Preheat oven to 350 degrees. Clean peppers, scrape out the center and remove seeds. Put peppers in a pot of boiling water, cooking them until they are done. Remove peppers from pan and place on paper towel until cool enough to handle.
In medium bowl mix ground beef, chopped onion, raw egg, cooked rice, salt and pepper. Mix together thoroughly by hand.
Place each pepper upright in a casserole dish. By hand, pack each one with ground beef mixture until all peppers are filled. Pour tomato sauce over all. (You may need to add a little water to bottom of casserole dish).
Cover with lid or aluminum foil and bake for
1 hr or until ground beef is done.