stir-fry the ginger, garlic, and scallions in the oil for a few seconds, then add the remaining marinade ingredients. Reduce the heat and simmer the mixture for 2 or 3 minutes, then pour it into a bowl to cool.
Pour the cooled marinade into the inflated duck through the tail vent. Skewer the tail shut. Tie a string at the neck, and hang the duck to dry the skin for 1½ hours in front of a fan, 3 to 4 hours in a cool place. If you are not using duck with its head on, sew the neck flap closed and hang the duck from a hook through the neck.
Roast the duck on a rack over a pan of water according to this timetable:
15 minutes at 450 degrees, breast up
25 minutes at 350 degrees, breast up
35 minutes at 350 degrees, breast down
5 minutes at 450 degrees, breast down
10 minutes at 450 degrees, breast up
Total time: 1 hour 30 minutes
Baste after each interval with the basting liquid.
When the duck is done, open the tail vent and let the marinade drain into a bowl.
Cut up the duck Chinese-style. Arrange it on a platter. Serve the degreased marinade on the side or poured over the duck.
May be served immediately or prepared ahead and served at room temperature.
Suggested Beverage: Medium-bodied Cabernet Sauvignon or Bordeaux