Combine the first three ingredients, coat the duck and let stand 2 hrs. Fill a steamer pan with water 4 cm deep. Place duck on rack breast side up, reserving marinade . Cover, bring water to boil and steam 30 min. Skim fat from steaming juice and reserve. Preheat oven to 200ºC . Transfer duck to a baking dish and brush with reserved marinade. Roast uncovered 15 min. Lower heat to 350 and roast a further 40 min. Remove duck to a cutting board. Skim and discard fat from the pan juices. In a small pan, combine reserved steaming and roasting juices, bring to a simmer, add the starch mix and cook, stirring, until thickened. Cut the wings, legs and thighs at the joints, split the back in half and the breast into quarters. Arrange pieces on a platter and top with the gravy.