Preheat oven to 350°F.
Combine uncooked ground beef, instant rice, chopped onion, minced garlic, and beaten egg in a large bowl. Season with salt and pepper to taste.
Wash green peppers, cut off the tops, and remove all seeds and membranes.
Stuff each pepper with the meat mixture, packing gently but firmly.
Place stuffed peppers upright in a 9x13 inch baking dish.
Mix tomato sauce and tomato soup together and pour over peppers, ensuring sauce covers ¾ of each pepper.
Cover with foil and bake for 3 hours or until peppers are tender and meat is cooked through.