In a small bowl, combine warm water, warm soy milk, active yeast, 1/2 of sugar and oil. Whisk and let yeast and sugar dissolve for 10 minutes.
Meanwhile, in a large mixing bowl, combine flour, remaining 1/2 of sugar, baking powder and salt into stand mixer. You can also mix by hand too.
Once wet mixture has risen, pour wet ingredients into dry ingredient mixture. Use a dough mixing hook. Start slow speed to slowly incorporate all the ingredients together on medium speed until it becomes a dough shape. Keep kneed for 3 to 4 minutes on medium-high speed. The dough should be elastic, but should not stick to your fingers or mixing bowl.
Remove the dough from the mixing hook and form as a ball. Place back into the bowl, cover with plastic wrap and let it rise in a warm place for 2 hours. It should rise to triple the size. Let it sit longer if needed.
Once dough has risen, place on a clean working surface. Roll out the dough to 1/4 inch thickness. Cut the dough 3 1/2 inch circles with a cookie cutter or glass. I was about to cut out 15 bao buns.
Lightly brush oil onto one surface of the bao buns and fold in half. Gently press each bao bun with a roller and place in a steamer lined with parchment paper. Cover with a lid and let the bao rest for 30 minutes.
While bao is resting, bring a large steamer pot or wok of water to a boil. Carefully place the steamer with the baos on top of the boiling water with lid. Make sure the water does not touch the bao buns. Cover and steam for 8-15 minutes.
When they are done cooking, open the lid to slowly bring air to the buns for 2 minutes. You can use a little bit of water on your finger to help remove parchment paper from the bao buns if they are sticking.
Use your favorite fillings inside of the buns and enjoy!
