In a mixing bowl, whisk together the golden syrup, vegetable oil, and baking soda until the mixture becomes smooth and glossy. Gradually add the all-purpose flour in increments, stirring to combine. Once the dough begins to come together, knead it gently until it forms a soft, pliable texture. Cover the dough with plastic wrap and let it rest at room temperature for 1 hour.

Portion the lotus seed paste into small balls, approximately 30g each. If incorporating salted egg yolks, press a halved yolk into the center of each lotus paste ball, then carefully reshape it into a smooth sphere, ensuring the yolk is fully enclosed.

After the dough has rested, divide it into smaller portions, each weighing about 20g. Roll each portion into a thin, even circle. Wrap the dough around a prepared filling ball, sealing the edges completely to encase the filling. Roll gently between your hands to form a smooth, seamless sphere.

Lightly dust a mooncake mold with flour to prevent sticking. Place the dough-wrapped filling into the mold and press firmly to shape. Gently release the mooncake by tapping or lifting the mold carefully.

Preheat your oven to 180°C (350°F). Arrange the shaped mooncakes on a baking tray lined with parchment paper, ensuring they are spaced apart. Apply a thin layer of egg wash using a brush, then bake for 5 minutes. Remove the mooncakes from the oven and let them cool slightly before applying a second layer of egg wash. Return to the oven and bake for an additional 10–15 minutes, or until the mooncakes are beautifully golden brown.

Transfer the baked mooncakes to a wire rack and allow them to cool completely. For the best flavor, store the mooncakes in an airtight container for 1–2 days to let the flavors develop and the crust soften slightly. Enjoy these traditional treats with your favorite tea!