Cut off the stems of the peppers and remove the seeds.Brown the beef.Saute the onion until it's limp. Mix the remaining ingredients in a bowl and fill the peppers with the beef mixture.
Place them in a deep dutch oven type pot, a cast deep iron skillet will also work. Add about 1 quart tomato juice in the pot. Cover and simmer adding a tomato juice if needed. Cook for 45 to 60 minutes pepper are soft.