In a large pot, heat the olive oil over medium heat. Brown the beef and onion until the beef is no longer pink. Add the garlic for the last minute of cooking. Drain.
Add the beef broth, tomato sauce, diced tomatoes, and green bell peppers. Bring to a boil and reduce heat to a simmer uncovered for about 30 minutes or until peppers are tender. Add salt and pepper to taste.
While soup is simmering cook rice according to the directions.
Stir in the cooked rice right before serving. If you want it thicker, add more rice. The rice will absorb the liquid so it's best stirred in right before.
If storing the soup in the fridge store the soup and rice separately.