Directions

Make the Filling

1. Steam 2 salted egg yolks over medium heat for 15 minutes (start counting the time after the water has come to a boil). If you don't have salted egg yolks, please use two fresh chicken yolks + 1/3 tsp of salt. Here is an easy demo video to make homemade salted egg yolk - https://youtu.be/tEjX3ZqOTG0
2. Press the yolk with a heavy-duty cleaver and slide it against the cutting board until the yolks turn into a fine powder. If you don't have a cleaver, crush the yolk with a fork, a blender, or a food processor.
3. Let the yolk powder go through a sieve into a sauce pot, then add 80g of milk (reserve about 40 grams to adjust the texture later), gelatin powder, unsalted and melted butter, fresh egg yolk, cornstarch, and sugar. Mix well.
4. Stir the mixture over low heat for about 8 minutes or until the mixture thickens into a paste.
5. Turn off the heat, add the reserved milk, and stir until the mixture becomes fluent; chill it in the fridge for 1 hour.

Make the Wrapper

1. While waiting, we can make the wrapper.
2. Thoroughly stir the yeast, sugar, and water, then let it sit for 5 minutes.
3. Pour the yeast water into the flour and mix until a rough dough forms. Then add 1 tsp of room temperature butter and continue to knead until the butter is well absorbed, and the dough is smooth.
4. Cover the dough and let it proof for 1-1.5 hours or until it is doubled in size.

Divide the Filling

1. During this time, keep an eye on the filling. If it is solidified, give it a nice stir until the filling becomes malleable again.
2. Portion the filling into seven even pieces, 30 grams each. Roll each one into a smooth ball. Once you finish all seven pieces, cover them and chill them in the fridge to keep them firm.

Divide the Dough and Wrap the Buns

1. Once the dough is doubled in size, punch the dough to eliminate the air bubbles. Then, knead it on the working surface for 6-8 minutes until all the air bubbles are gone.
2. Divide the dough into 7 pieces, 50 grams each. Shape each one into a smooth ball. Cover them with a damp towel.
3. Start with the first ball that we shaped, dust it with some flour to prevent stickiness, and flatten it into a small round patty. Next, one hand uses a rolling pin to roll the edge of the dough back and forth. The other hand rotates the dough. Repeat that, and you will get a round wrapper with a thick middle and a thinner edge. The diameter should be 5 inches.
4. Take the gooey custard filling from the fridge, put one in the middle of the wrapper, and press it down to compact tightly. Next, use your forefinger and thumb to squeeze it around and push the wrapper up. When you get to the end, lightly wet the edge with water, then pinch to close the bun.
5. Place the bun, rough side down, on a piece of parchment paper and continue to wrap the rest.
6. Place the buns on a steamer rack, leave some space between each other; cover them, and let them proof for 20 minutes.
7. Fill the steamer pot with water and turn the heat to high. Steam the buns for 8-10 minutes (start counting the time after the water comes to a boil).
8. Turn off the heat but wait 10 minutes to open the lid. If you open the lid too early, the buns will shrink when contacting the cold air, and you will lose the fluffiness.