01 - Preheat oven to 350°F. Line a baking tray with parchment paper.
02 - In a bowl, combine golden syrup, vegetable oil, and alkaline water. Stir until smooth and well incorporated.
03 - Add flour to the wet ingredients and mix until a soft dough forms. Cover and let rest for 30 minutes at room temperature.
04 - Divide lotus seed paste into 12 equal portions (approximately 1.4 oz each). If using salted egg yolks, place one yolk in the center of each paste portion and shape into a smooth ball, completely enclosing the yolk.
05 - Divide the rested dough into 12 equal pieces (approximately 0.9 oz each).
06 - Flatten one piece of dough into a disc. Place a filling ball in the center and gently wrap the dough around it, sealing completely. Repeat for all portions.
07 - Lightly dust each ball with flour. Place into a floured mooncake mold and press firmly to imprint the design. Invert the mold and gently release onto the prepared baking tray.
08 - Bake for 5 minutes, then remove from oven and let cool for 10 minutes.
09 - Whisk egg yolk and water together until combined.
10 - Brush a thin layer of glaze over the mooncakes. Return to the oven and bake for an additional 15 to 20 minutes, or until golden brown.
11 - Cool completely on the baking tray. Transfer to an airtight container and store for 1 to 2 days before serving to allow the pastry skin to soften and develop proper texture.