Clean duck. Wipe dry and tie a string around neck.
Hang duck in cool, windy place 4 hours.
Fill a large wok with water. Bring to boil. Add ginger, scallion, honey, vinegar, and sherry. Bring to boil. Pour in dissolved cornstarch. Stir constantly.
Place duck in a large strainer above the larger bowl. Scoop boiling mixture all over duck for about 10 minutes.
Hang duck again in cool, windy place for 6 hours until thoroughly dry.
Place duck breast side up on a greased rack in oven preheated to 350 degrees. Set a pan filled with 2 inches of water in the bottom of the oven.
(This is for drippings). Roast 30 minutes.
Turn duck and roast 30 minutes more. Turn breast side up again. Roast 10 minutes more.
Use a sharp knife to cut off the crispy skin. Serve meat and skin immediately on a prewarmed dish.
The duck is eaten hot with hoisin sauce rolled in Mandarin Crepes. Garnish with scallion flowerets.
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.