Cantonese steamed custard buns, gooey style

Put the salted egg yolks in a heatproof bowl in a steamer over boiling water and cook over medium heat 15 minutes.

Crush the steamed yolks with a heavy cleaver, pressing firmly and sliding the blade until smooth.

Put the yolk in a sauce pot with two thirds of the milk, reserving about 40 grams. Stir in the gelatin powder until evenly distributed.

Add the melted butter, the fresh egg yolk, the cornstarch and the sugar and mix well, making sure the cornstarch is evenly distributed before cooking.

Stir over low heat about 5 minutes until it thickens. Keep whisking until the starch is fully gelatinized, above 165 degrees Fahrenheit, which shows as bubbles popping up.

Cover and chill in the fridge about 1 hour. The gelatin sets cold and melts to a liquid when heated, which is what makes the filling gooey.

Stir the yeast and sugar into the water and leave about 5 minutes to bloom, until foamy.

Pour the yeast water into the flour, stirring at the same time, and knead until a rough dough forms.

Add the room temperature butter and keep kneading until it is absorbed and the dough is smooth.

Cover and proof one to one and a half hours, until doubled in size.

Stir the filling until malleable again and portion it into 7 balls of about 30 grams, rolled between the hands. Cover and return to the fridge so they stay firm.

Dust a finger with flour and poke a half inch hole in the risen dough; if the hole remains it is ready.

Punch the dough down and knead it on the work surface 6 to 8 minutes, using the palm and body weight to open and spread it, breaking up the air pockets.

Check by cutting the dough open: irregular holes mean more kneading, a smooth cut surface with small even holes means it is degassed.

Divide into 7 pieces of about 50 grams and shape each into a smooth ball by pressing, folding in half, turning and repeating, then round it with both hands.

Dust a ball with flour and roll it flat with a rolling pin, flipping and rolling the edge thinner so the wrapper is thick in the middle and thin at the edge, about 3.5 inches across.

Put the filling in the middle, press it down against the wrapper so no air is trapped, squeeze the wrapper up with forefinger and thumb, wet the edge with a little water and pinch it closed.

Set rough side down on parchment paper and shape it taller so it does not go flat. Space the buns on the steamer rack.

Cover and proof 20 more minutes.

Set above the water on high heat; when steam comes out, drop to medium low and steam 8 to 10 minutes.

Turn off the heat and leave the lid on at least 10 minutes so the buns do not shrink in the cold air.

To store, freeze after steaming and re-steam from frozen over medium heat 15 to 20 minutes.