They were one of the most exciting dim sum items I ever tasted in Singapore — you make a bite and watch how hot golden lava slowly flows out. That lava is an unusual custard based on salted duck egg yolks and condensed milk. Steamed buns are served hot with hot green tea.
I found Patricia Wu’s recipe five years ago and have been mastering it since then. I learned there is a difference between the taste of homemade salted egg yolks and those I can get at Asian stores in Austin. The best tasting duck yolks were Taiwanese so far, yet they were also bland in comparison to homemade. If you care for bright egg yolk yellow colors, use coloring. The best way to get natural egg yolk yellow is to add a drop of pink coloring to the yellow one.
Making Golden Lava Steamed Buns
What can I say? They are addictive for those who crave for rich milk and egg flavors, creamy and fluffy textures, and a delicate, sweet and salty balance.
In a bowl, combine sweetened condensed milk and corn starch using a whisk.
Finely chop egg yolks and combine them in another bowl with evaporated milk.
Transfer the contents of both bowls into a blender jar and process until smooth.
Transfer the mixture to a saucepan, add salt and coloring, and bring to simmer over medium heat, constantly stirring with a whisk. Cook to thicken for 1-2 minutes, vigorously stirring with a whisk. Turn off the heat, continue whisking and let it cool down until it stops steaming. Add butter and emulsify it into the custard with a whisk. Transfer the custard to a container, cover it with plastic wrap, so it contacts the surface of the custard. Refrigerate until ready to shape buns.
Make a white dough. Measure and combine all ingredients, knead dough, shape it into a ball, place into a bowl and cover with plastic wrap. Leave at room temperature (74F) for 1 hour for rising.
Make a yellow dough. Add yellow coloring to measured milk. Measure and combine all ingredients, knead dough, shape it into a ball, place into a bowl and cover with plastic wrap. Leave at room temperature (74F) for 1 hour for rising.
After the dough doubles in volume, dust your working surface with some flour and roll each one into 8" x 30" rectangular, ~1/8" thick. Just like with any other elastic dough, do it in three steps, giving it 5 minutes of rest in between.
Place one dough rectangular on top of another and roll them into a 8" long cylinder. Cover it with a towel and let rest for 15 minutes.
Cut the dough cylinder into 1/4" thick round slices.
Dust your working surface with some flour.
Using a rolling pin, flatten each slice to make it 1/8" thick.
Keeping the center of each round 1/8" thick, flatten the edges to make them 1/16" thick.
Place 2 tbsp of custard in the center.
Connect the edges by making tiny folds on the bottom of the bun.
Line steaming baskets with parchment paper sprayed with vegetable oil and arrange buns giving them enough space to double during the cooking. Cover and let them rise for 30 minutes at room temperature. At the end of this step, buns are ready to steam or to freeze. Steam frozen buns without thawing, right from the freezer.
Steam buns for 7 minutes (or 10 minutes for frozen). Serve with hot green tea.