Optional marinating: You can place the chicken pieces in a plastic zipper bag, pour the sauce into the bag and shake to coat. Refrigerate to marinate up to 8 hours before cooking.
Preheat oven to 350F (regular bake setting/not fan assisted).
Pat chicken pieces dry with paper towel and season lightly with salt and freshly ground pepper. Place into an oven-safe baking dish.
Prepare the sauce by stirring together all the sauce ingredients. Pour sauce over chicken pieces to coat.
Place uncovered into preheated oven and cook for 1 ½ hours, basting with the sauce every 30 minutes (so after 30 and 60 minutes of cooking). At end of cooking, if you like, switch oven to Broil (without raising rack) and broil 1-2 minutes to brown up a bit.
Serve garnished with sesame seeds and sliced green onion, if desired.
