Prepare the yolks and filling: gently rinse the Salted Duck Egg Yolks and steam or bake them for 5–8 minutes until just set; let cool. Divide the White Lotus Seed Paste into portions large enough to form a ball around each yolk, then press paste around each cooled yolk to form smooth filling balls.
Make the dough base: in a mixing bowl combine the Golden Syrup, Peanut Oil and Lye Water until smooth and homogenous.
Add the dry element: sift the All-Purpose Flour into the syrup mixture and gently fold until a shaggy dough forms; if the dough is too dry, add a teaspoon of Water at a time until it comes together into a soft, pliable ball.
Rest the dough: cover the dough with plastic wrap and let it rest at room temperature for 30 minutes to relax the gluten and allow the syrup to hydrate the flour.
Portion and assemble: weigh or estimate portions so each mooncake has the desired balance (a common ratio is about 2 parts filling to 1 part dough by weight). Roll each dough portion into a round, flatten into a disc, place a filling ball in the center, and carefully wrap the dough around the filling, sealing the edges and rolling into a smooth ball.
Mould the mooncakes: dust a mooncake mould lightly with flour, place a filled ball into the mould, press firmly to shape and imprint the pattern, then release onto a lined baking tray.
Preheat and initial bake: preheat the oven to 180°C (350°F). Bake the shaped mooncakes for about 8–10 minutes until the surface begins to set.
Egg wash and final bake: beat the Egg Yolk with a teaspoon of Water and brush a thin coat over each mooncake. Return to the oven at 160°C (320°F) for another 12–15 minutes, or until the cakes are evenly golden; if you prefer a deeper color, apply a second light egg wash halfway through the final bake.
Cool and mature: remove the mooncakes from the oven and let them cool completely on a rack. For best texture and glossy appearance, store them in an airtight container at room temperature for 24 hours to allow the crust to soften and flavors to marry before serving.
