Heat oven to 350. In a shallow dish combine the flour, garlic powder and pepper. Dip each piece of chicken in flour mixture and coat evenly.
Pour melted butter in a shallow baking dish, large enough to accommodate chicken in a single layer. Arrange chicken in pan and bake uncovered for 30 minutes.
Meanwhile, in a medium saucepan combine water, orange juice, rice vinegar, soy sauce, orange zest and whisk over medium heat for a few minutes. Then stir in brown sugar, ginger, and garlic and let it come to a boil. With a whisk combine cornstarch with water. Whisk until dissolved and add it to the sauce until thickened.
After chicken has baked the 30 minutes, turn each piece over and pour 1/2 sauce mixture evenly over chicken. Bake another 30 to 40 minutes. Bast occasionally.
Serve chicken over rice with extra sauce on the side.