To a slow cooker add the onion, teriyaki sauce, rice vinegar, minced garlic, minced ginger, and garlic powder. Stir well. Add the chicken on top and coat the chicken in the sauce.
Cook on LOW for 5-6 hours or HIGH for 3-4 hours.
Once the chicken is cooked, shred and continue to cook for 20 minutes in the slow cooker.
Serve over rice with green onions and sesame seeds. Enjoy