1. Heat the olive oil in a large skillet over medium heat.
2. Add the green pepper, onion and garlic.
3. Cook for about 2 minutes or until onion is translucent.
4. Place in the bottom of a crock pot.
5. Add the salt, pepper, beef stock, tomatoes, mushrooms and barbecue sauce.
6. Stir well.
7. Cover and cook on low setting 8 hours.
8. Mix together the water and cornstarch in a small bowl.
9. Add to the crock pot just before serving.
10. Mix well to thicken sauce.
11. Serve over rice.