Balsamic Chicken

1.5 - 2 lbs. b/s chicken breasts (chicken can still be frozen)
1/2 cup Olive Oil
1 cup Balsamic Vinegar
2 (14 oz) cans Diced Tomatoes
1 (8 oz.) can Tomato Sauce
3-4 cloves garlic, minced
2 tsp. dry oregano

put chicken in crockpot. Combine all other ingredients and pour over the chicken. Cook on low for 6-8 hours. Shred chicken with a fork and serve over rice or pasta