Brown the beef on all sides in the oil. Add V8 juice, canned tomatoes, soup mix and frozen vegetables. (At this point, additional tomato juice or water can be added, if desired, but this is a vegetable-thick soup.) Bring ingredients to a boil, then simmer for at least 4 hours (or put in slow cooker). Remove roast from the soup, cut into bite-sized pieces or shred and return to soup mix.