2Tablespoonscanola oilor other neutral-flavored cooking oil (plus more to brush the dough)
1Tablespoongranulated sugar
Instructions
Whisk together 2 cups all-purpose flour, 2 Tablespoons cornstarch, 1 teaspoon instant yeast, 1 teaspoon baking powder, and 1/4 teaspoon salt in the bowl of a stand mixer. Set aside.
In a measuring cup, stir together 3/4 cup warm water, 2 Tablespoons canola oil, and 1 Tablespoon granulated sugar. Attach a dough hook to the stand mixer and turn the mixer on low speed while slowly pouring in the water mixture.
Continue to knead the dough in the mixer until all of the flour mixture is incorporated and the dough forms a ball. Turn off the mixer and move the dough to a clean countertop. Knead the dough until it forms a smooth ball, about 30 seconds. Place the ball to rise in an oiled medium bowl and cover with plastic wrap or a lid. Let the dough rise at room temperature for about an hour, until it has doubled in size.
While you're waiting for the dough to rise, cut 12 3-4" parchment paper squares. You can also go ahead and get your steamer set-up ready. Find a large skillet that is just bigger than your bamboo steamer (a 12" skillet is the perfect fit for a 10" steamer). Fill it with a small amount of warm water (making sure that the water does not touch the bottom of the steamer) and set the steamer into the skillet.
Divide the dough into 12 equal pieces (the easiest way to do this is to form the dough into a rope and cut into 12 pieces, but the most accurate way is to weigh the dough and divide the total weight by 12).
Working with 1 piece of dough at a time, and keeping the rest of the dough covered, form the dough into a ball, then use a rolling pin to roll the ball into an elongated oval. Lightly brush the top of the oval with more canola oil. Fold the oval in half and place it on one of the parchment squares. Place it into the bamboo steamer to rise. Repeat with the remaining pieces of dough. If you can't fit all of the buns into your steamer at once, place the remaining buns on a plate or baking sheet and cover with plastic until you're done with the first batch.
Once you've filled your steamer, let the buns rise for another 30 minutes until they become puffy. Then turn the heat on high until the top of the steamer is hot and you see steam starting to come from the steamer. Turn the heat to medium and continue to cook for 10 minutes. Turn the heat off and leave the steamer in place - do NOT open it (this will cause the buns to deflate and become tough and doughy). Let the buns rest in the hot steamer for 5 minutes. Remove the buns from the steamer and serve immediately, or place them somewhere to keep warm if you need to cook a second batch.
Serve the buns with your desired fillings. Any leftovers can be placed into a zipper bag and stored at room temperature for a day or so, or frozen.