Mix the ground beef, mixed vegetables, 1 can of tomato sauce, rice, onion, green onions, garlic, egg, salt, and black pepper in a large bowl until thoroughly combined. Spoon the beef mixture into the bell peppers. Arrange peppers in a baking dish, and spoon the remaining 1 can of tomato sauce on top. Cover with aluminum foil.
Bake in the preheated oven until the beef is no longer pink, about 1 1/2 hours.
