Steamed Buns with Ground Pork Filling, Salted Egg, and Chinese Sausage
Steamed Siopao Dough: (enough for 12 buns)
1 cup lukewarm water
1 tsp active dry yeast
5 tbsp granulated sugar
2 cups all-purpose flour
1 cup cornstarch
1/4 cup vegetable oil
2 1/2 tsp baking powder
Pork Bola-Bola Filling:
1 cup ground pork (about 1/2 lb)
1/4 tbsp pickle relish
2 cloves garlic, minced
2 tbsp oyster sauce
1 tbsp sesame oil
1/4 cup yellow onion, minced
1/4 cup scallions, minced
1 tsp salt
1/2 tsp ground black pepper
2 Chinese sausages (cut into 12 pieces total)
3 salted eggs (peeled and quartered)
2 tbsp white vinegar for steaming (optional)
Siopao Dough Part 1:
Take the bowl of your stand mixer, add 1 cup of lukewarm water (we used warm water from the tap - temp should be around 105-115 F or 40-45 C) and sprinkle in 1 tsp of active dry yeast. Whisk until the yeast has dissolved into the water.
Add in 5 tbsp of granulated sugar and whisk this in till dissolved. Add in 1/4 cup vegetable oil, and mix it in.
In a separate mixing bowl using a sieve, sift together 2 cups of AP flour and 1 cup of cornstarch. Add this mixture of dry ingredients into the yeast-water mixture. With your hands, gently combine the wet and dry ingredients so that all the dry ingredients are moistened.
Fit the mixer with the dough hook attachment, and turn on the mixer to the very lowest setting on your mixer ("stir" setting in our stand mixer), and let it mix until the dough is smooth, about 10 minutes. The dough should not be sticking to the bottom or the sides of the bowl. If kneading by hand, this usually takes about 15 to 20 minutes.
When the dough has come together, it should look smooth. Turn off the mixer. Leaving the bowl still attached with the dough hook, cover the dough with a damp cloth (or plastic wrap), and let it rest at room temperature for 2 hours.
Pork Siopao Bola-Bola Filling:
In a large bowl, add in 1 cup ground pork, 1/4 cup pickle relish, 2 cloves minced garlic, 1 egg, 1 tbsp oyster sauce, 1 tbsp sesame oil, 1/4 cup yellow onion, minced, 1/4 cup scallions, minced, 1 tsp salt, and 1/2 tsp ground black pepper. Mix this till together until this pork mixture is well combined. Line a sheet pan with parchment paper, and divide the filling mixture into 12 equal portions onto the parchment paper. Set this aside in the fridge for now.
Cut 2 Chinese sausages into 12 pieces total (cut each sausage link into 6). The sausages we used were 40 g per link, about 80 g total.
Peel 3 salted eggs, and quarter each egg, to make a total of 12 pieces of salted egg.
Siopao Dough Part 2:
When the dough has rested for 2 hours, remove the cloth, and sprinkle 2 1/2 tsp baking powder over the dough.
Turn on the mixer with hook attachment back on to the very lowest speed ("stir" on our machine). Let it mix for 3 minutes, or until the baking powder is mixed in and the dough looks smooth again.
Re-cover with the cloth (or plastic wrap) and let it rest for 20 minutes.
In the meantime, cut twelve 3" x 3" squares.
Assembling and Cooking the Siopao Buns:
Turn the dough onto a smooth clean surface, roll it into a long tube, and divide it into 12 approximately equal pieces, estimating by eye and weight in your hands.
Form the dough into tight spheres by rolling each piece in your palms with cupped hands - do this for all 12 pieces. This ensures that there are no air bubbles in the dough. Then set them aside to rest under a cloth to prevent them from drying out.
Then take 1 sphere at a time, and use a rolling pin to flatten each sphere into a circular disc shape that's about 4 inches in diameter. The thickness of the dough should taper towards the edges of the circle - i.e. the disc should be thicker in the center and thinner around the edges.
Add one portion of filling (previously divided earlier) in the center of the circle. Put 1 piece of salted egg and 1 piece of Chinese sausage on top of the filling. Fold the dough disc together by bringing the opposite sides of the circle together, and then pinching the closed circle together tightly, then twisting the top, to ensure the bun is sealed.
Invert the bun placing it seam-side down on one of the 3" x 3" squares of parchment paper. And shape it with your hands as necessary to create a more even circular shape.
Repeat this with the other 11 pieces of dough and remaining portions of filling. Cover the formed buns with plastic wrap as you're forming the remaining buns, to prevent the formed buns from drying out.
When you're ready to steam the buns, prepare a steamer on medium-high heat, with the pot filled about 1/4 of the way up. Add in an optional 2 tbsp of white vinegar to the water. This creates whiter looking buns when they are cooked.
When the water is boiling and the steamer is preheated, turn down the heat to medium-low, brush the buns you're about to steam with some water immediately before adding them to the steamer, then place them in the steamer. Brushing with water will help the buns maintain a smooth surface during steaming. Close the lid, and steam over medium-low heat for 15 minutes for each batch. Do not open the lid during that time.
Depending on the size of your steamer, steam the buns in batches with a minimum of 1" gap in between the buns and 1/2" from the walls of the steamer, as they will expand while steaming. We're steaming our buns in six batches, with 2 buns in each batch.
You can store uncooked formed buns in the freezer in an airtight container. Cook frozen buns in the same way as described above, with about 5 minutes extra steaming time, for a total of 20 minutes.
Leftover cooked buns should be stored in an airtight container, and will keep in the fridge for up to 5 days, or in the freezer for up to 2 months. Reheat by steaming on medium-low heat for 15 minutes.