Egg Yolk Bun Recipe

Activate yeast and mix dough

Warm the milk to about 40°C (lukewarm). Stir the instant dry yeast and 1 tablespoon sugar into the warm milk and let sit 5 minutes until foamy. In a large bowl, combine 2.5 cups flour, remaining 1 tablespoon sugar and 1 tsp salt. Make a well, add the foamy yeast-milk and 2 tbsp vegetable oil. Mix with a wooden spoon until it starts to come together.

Knead the dough on a lightly floured surface for about 8–10 minutes until smooth and elastic. If dough is sticky, sprinkle up to 2 tbsp additional flour, but keep dough soft. Shape into a ball.

Place the dough ball in a lightly oiled bowl, cover with plastic wrap or a damp towel, and proof in a warm place for 45–60 minutes or until doubled in size.

After the first rise, punch down the dough to release air and let rest 5 minutes before dividing.

Prepare yolks and dry mix

If salted egg yolks are raw, steam them for 5–6 minutes until set, then mash with a fork. In a small bowl, combine custard powder, powdered sugar and milk powder (if using). Stir to combine.

Cook custard

In a small saucepan over low heat, melt 3 tbsp unsalted butter. Add the mashed salted egg yolks and stir until smooth. Add evaporated milk and sweetened condensed milk and mix. Sprinkle in the dry custard/powdered sugar mix while stirring constantly to avoid lumps.

Continue cooking the mixture over low heat for 3–5 minutes, stirring constantly, until it becomes thick and glossy but still pourable. Remove from heat and stir in 1 tbsp black sesame paste to create the 'black gold' color and flavor. Taste and adjust sweetness by adding a little extra condensed milk if desired. Let cool to room temperature, then chill in the fridge until slightly firm but still scoopable (about 30 minutes). This makes the runny, molten filling.

Portion dough and filling

Divide the proofed dough into 3 equal pieces (about 110–130 g each depending on final dough yield). Dust work surface lightly with the 0.25 cup flour. Flatten one piece into a 4–5 inch round, pressing from center outward to make edges thinner than center.

Place approximately 2–3 tablespoons (about 45–60 g) of the cooled custard filling in the center of each dough round. Be sure the filling is not too hot and is thick enough to keep shape; if too loose, chill longer.

Seal buns

Brush a little vegetable oil around the edge of the dough if needed to prevent sticking. Gather edges up and pinch to seal tightly, twisting once to secure. Roll gently between your palms to form smooth, round buns. Place each bun seam-side down on a small square of parchment paper.

Second proof

Cover the formed buns with a damp towel and proof for another 20–30 minutes until slightly puffy (they will expand more in the steamer). Meanwhile, prepare a steamer with about 1 cup water and bring water to a simmer.

Steam buns

Place buns in the steamer basket with spacing for expansion. Steam over medium-high heat for 10–12 minutes. Do not open the lid during steaming. After 10–12 minutes, turn off the heat and let the buns sit in the closed steamer for 2 minutes before opening to prevent sudden collapse.

Carefully remove buns and serve immediately while the custard inside is molten and runny. If you must hold, keep warm but note the filling will thicken as it cools.