Whisk peanut butter with soy sauce, sherry, garlic, ginger, pepper, sugar, sesame oil and onions. Pour over chicken pieces and marinate overnight or up to 24 hours.
Heat oven to 450. have ready a buttered 9 x 13 inch baking pan or coat it with nonstick cooking spray.
Reserve marinade. Bake chicken in pan to sear meat on all sides. Lower heat to 350 and bake 1 1/2 hours, basting with reerved marinade first hour of baking. Discard remaining marinade. Put chicken on serving platter. Cover with foil. Pour off excess fat from drippings. Stir honey with mustard. heat and mix with chicken drippings. Cook over low heat til drippings are dissolved, then pour sauce over cooked chicken and serve. Makes about 6 servings.