Homemade vegetable beef soup

I made a roast with potatoes and carrots in the crock pot yesterday. I am always left with a little piece of roast that is not enough to feed us another meal so I always make soup with it. I pour all the juice from the crock pot into a large pot. I add a can of petite diced tomatoes or tomato puree, corn, butterbeans, green beans, or really whatever I have around. I add all juices from either the can or the cooking liquid if I am using leftover vegetables from the refrigerator. If I am using frozen vegetables I add a little water. I tear the roast into small pieces and chop the potatoes and carrots into smaller pieces also. Let this simmer about 20-30 minutes.