Flaky egg yolk pastry with rich salted egg yolk and red bean filling is a festive treat. A family recipe with buttery, fresh layers.
Make the water dough: In a bowl, combine 1 cup flour, 3 tbsp butter, 2 tbsp lard, 2 tbsp sugar, 0.5 tsp salt, and 7 tbsp water. Mix and knead gently until a soft dough forms. Cover with a damp towel and let rest for 20 minutes.
Make the oil dough: In a separate bowl, mix 1 cup flour with 3 tbsp butter and 2 tbsp lard until a pliable dough forms. Shape into a log. Let rest for 15 minutes to relax the gluten.
Divide both doughs into 8 equal pieces. Flatten a water dough piece and wrap an oil dough piece inside it. Seal and shape into a ball. Repeat for all portions.
Flatten each ball into an oval. Roll up tightly from one end to form a log. Turn 90°, roll out again, and roll up. Wrap each with sweet red bean paste and a salted egg yolk in the center. Seal and shape into a round pastry.
Arrange pastries on a baking sheet lined with parchment. Brush tops with egg yolk mixed with milk. Sprinkle with sesame seeds. Bake in a preheated oven at 350°F (175°C) for 28–32 minutes until golden brown and the layers are crisp. Cool on a wire rack before serving.