Pat the Whole Duck dry inside and out; season the cavity generously with Kosher Salt and set aside for 15–30 minutes to draw out excess moisture.
Bring a large pot of Water to a rolling boil. Carefully ladle or pour the boiling water evenly over the duck to tighten and slightly set the skin, then pat the bird dry with paper towels.
Make the glaze by gently warming a few tablespoons of Water with Maltose and Rice Vinegar until the maltose dissolves and the mixture is syrupy; keep warm so it spreads easily.
Brush the glaze all over the duck skin, place the duck on a rack, and air-dry in the refrigerator (or hang in a cool, ventilated place) for at least 8 hours or overnight until the skin is dry to the touch.
Preheat the oven to 475°F (245°C). Roast the duck breast-side up for 10–15 minutes at this high heat to begin rendering fat and crisping skin, then reduce the temperature to 350°F (175°C) and continue roasting for 40–60 minutes more, or until the skin is deeply browned and the internal temperature in the thigh reaches 165°F (74°C). Drain excess fat from the roasting pan as needed.
While the duck rests, make thin pancakes: combine All-Purpose Flour with warm Water to form a soft dough, knead briefly, let rest 20–30 minutes, then divide, roll very thin and cook briefly on a hot skillet, brushing each pancake with a little Sesame Oil to keep them pliable.
Prepare the garnishes: cut the Scallions into long thin batons; slice the Cucumber into matchsticks and toss with a pinch of Fine Salt to draw out water, then pat dry.
Carve the duck into thin slices, arranging skin and meat together. Serve by placing slices in a pancake with scallions, cucumber and a dab of Tian Mian Jiang; roll and enjoy immediately.
