1. Heat olive oil in a large pot.
2. Add onions; cook for 5 minutes.
3. Add tomatoes and BBQ sauce; simmer on medium-high heat for 10 minutes.
4. Add beef; reduce heat to a low simmer; cover and slow cook about 3-4 hours or until beef is very tender.
5. Remove meat from pot and set aside.
6. Increase heat, remove cover, and cook liquid down until thick stirring often.
7. Return meat and shred with a fork. Warm through, salt and pepper to taste.
8. Serve on fresh sandwich rolls.