Chicken Taco Stew

1 onion, chopped
1 16oz can black beans
1 16oz can kidney beans
1 8 oz can tomato sauce
2 15oz cans dice tomatoes/w chilies
1 packet of taco seasonings
1-2 boneless skinless chicken breast

Mix everything together in a slow cooker except chicken. Lay chicken on top and cover. Cook on low 6-8 hours or on high for 3-4 hours. 30 minutes before serving, remove chicken breast and shred with fork. Mix chicken in slow cooker and serve.

*NOTES* I already has shredded chicken from another diner (see One-Dish Chicken Supper). I got this recipe from a facebook group called The Crock Pot Recipe Exchange posted by Tara Francis.