Meanwhile, in 1-quart saucepan, heat orange peel, orange juice, jelly, lemon juice, mustard and salt to boiling. In small bowl, mix cornstarch and water; stir into sauce. Cook over medium heat, stirring constantly, until mixture thickens and boils. Boil and stir 1 minute. Stir in orange sections and liqueur. Brush duckling with some of the sauce. Serve with remaining sauce.