Prepare sugar water: Dilute maltose with clean water. If unavailable, boil white sugar with a small amount of water until bubbly and stringy, then dilute with water. Set aside.
Clean the duck and inflate it to separate the skin from the meat. Hold the neck over a pot of boiling water and scald the entire body with boiling water 3-4 times. Drain and invert.
Pour the prepared sugar water repeatedly over the duck until evenly coated. Hang in a cool place to dry. Ideal timing is 8-10 PM, leaving it in a corridor overnight. Northern spring temperatures around 3°C are perfect for drying.
Fill the dried duck with boiled peppercorn-seasoned water to 50-80% capacity. Sew the opening shut. Brush thoroughly with skin glaze (made from sugar water, honey, brown sugar, and white vinegar), ensuring even coverage on all surfaces and joints.
Preheat the oven to 220°C for 5 minutes. Place the duck on a rack with an oil-paper-lined baking tray underneath to catch drips. Position in the lower-middle rack.
After 5 minutes, check coloring. If slow, activate the convection fan. Rotate the rack after 10 minutes, bake another 10 minutes, adjusting temperature downward in 10°C increments if coloring is too dark.
Flip the duck, reapply glaze to pale areas, and bake 10 more minutes. Monitor and adjust temperature as before for even coloring. After 30 minutes, check internal doneness by observing juices: no pink liquid indicates readiness.
Brush the roasted duck with sesame oil. Slice after slight cooling. Serve with homemade pancakes, scallion strips, cucumber sticks, and sweet bean sauce. The duck features tender meat, crispy skin, and rich flavors.
For less oily options, prepare oil-free pancakes. The tender duck breast is ideal for elderly diners.