1 can (14-1/2 ounces) Italian-style stewed canned tomatoes, undrained
1 tablespoon ketchup
1/2 teaspoon dried oregano leaves
Heat oven to 350°F. Cut tops off bell peppers; remove seeds.
Combine ground beef, onion, rice, 3 tablespoons ketchup, salt, 1/2 teaspoon oregano and pepper in large bowl, mixing lightly but thoroughly. Spoon into peppers; stand peppers in 8 x 8-inch baking dish.
Combine sauce ingredients; pour over peppers. Cover dish tightly with aluminum foil. Bake in 350°F oven 1- 1/2 hours, until instant-read thermometer inserted into center of pepper registers 160°F.