Chun bing (春饼, spring pancakes) — also called the mo bing (薄饼, thin pancakes) used for Peking duck service — are the delicate, paper-thin wheat flour crepes in which Peking duck skin, cucumber, scallion, and sweet bean sauce are wrapped. The making of these pancakes is a distinct skill: the dough is made in pairs (two thin rounds of dough, each brushed with sesame oil, then placed together and rolled as one unit), cooked briefly on a dry skillet, then peeled apart to produce two extremely thin, pliable pancakes. The pancake must be so thin that the filling is visible through it when held to light.
The dough: 200g plain flour + 120ml just-boiled water. Mix with chopsticks while the water is still boiling. Knead 8 minutes. Rest 30 minutes. The hot-water dough produces a more pliable, delicate pancake than cold-water dough. The double rolling technique: Divide the dough into small pieces (approximately 15g each). Roll each piece into a ball. Flatten into a small disc. Brush the top of one disc with sesame oil. Place a second disc on top. Roll the two discs together as one unit — rolling them together ensures equal thinness for both. The combined disc should be approximately 20cm in diameter and almost translucent. Cooking: Cook the double disc in a dry, ungreased skillet over medium heat for 30-45 seconds per side. The pancake should develop faint brown spots but remain very pale overall. Carefully peel the two layers apart while still warm.
Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009); Fuchsia Dunlop, Invitation to a Banquet (2023)