oven at 350°
Cut tops off of the peppers & remove seeds. Set aside.
STUFFING in large bowl combine: hamburger, onion, rice, 3 tablespoons ketchup, salt, 1/2 teaspoon oregano & pepper. mix well. Spoon into prepared peppers. Stand peppers in a 8X8 square pan. Use foil to prop up peppers if necessary.
SAUCE in a smaller bowl, combine stewed tomatoes, 1 tablespoon ketchup & 1/2 teaspoon dried oregano. Pour over stuffed peppers. Cover dish tightly with tin foil.
Bake 1 & 1/2 hours to medium done. (Pepper should be at least 160°