Begin by thoroughly cleaning the duck. Insert a straw between the skin and meat, then gently inflate the skin to separate it from the flesh.
Bring a pot of water to a boil and repeatedly pour the hot water over the duck skin to tighten it. This step is typically repeated several times for optimal results.
Combine two tablespoons of maltose, one tablespoon of cooking wine, and one tablespoon of white vinegar in a bowl. Heat the mixture in a microwave for 30 seconds, then stir until well blended.
Use a brush to apply the glaze evenly over the duck, applying multiple layers to achieve a rich color during roasting.
Place the duck on a rack or prop it upright using a bottle. Allow it to air-dry in a room for approximately one day to crisp the skin.
Position the duck on a rack set over a baking tray lined with foil. Insert a steamed bun and an apple into the cavity, then secure the opening with toothpicks.
Preheat the oven to 350°F (175°C). Roast the duck for about 1.5 hours, turning it periodically to ensure even cooking.
Once roasted, the duck will appear glossy and golden. Let it rest briefly before slicing.
For serving, slice the duck to include both skin and meat. Traditionally, the slices are wrapped in spring pancakes with cucumber strips and scallions.
A bite of the pancake-wrapped duck delivers an exceptionally flavorful experience.