To make stuffed pepper soup, brown 1 pound ground beef with 1 cup diced onion over medium heat, and drain the fat from the mixture. Place the beef mixture in the slow cooker with 1 14.5-ounce can of diced tomato flavored with garlic and onion, 2 cups green pepper, 1 15-ounce can tomato sauce, 3 cups beef broth, 1 cup cooked rice and 1/2 teaspoon each dried basil and oregano. Cook on low for six to eight hours.
Alternately, brown 2 pounds ground beef, drain the fat, and place the beef in the slow cooker. Add 1 15-ounce can tomato sauce, 2 15-ounce cans tomatoes, 32 ounces beef broth, 1 cup chopped peppers, 1 diced onion, 3 or 4 cloves minced garlic, 2 tablespoons brown sugar and 1 cup water to the beef.
Season the soup with 2 teaspoons salt and 1 teaspoon black pepper, and cook on low for six to eight hours. Add 1 cup uncooked white rice to the soup, and cook for an additional 30 minutes.
To make vegetarian stuffed pepper soup, omit the ground beef and add soy crumbles to the soup. Exchange the beef broth for vegetable broth and cook as recommended for traditional stuffed pepper soup.