Whisk together the water and yeast in a small bowl. Let it sit for a few minutes.
Stir the flour, sugar, salt, and baking powder together in a large mixing bowl.
Stir 1 tablespoon of oil into the yeast and water mixture, then add the mixture to the dry ingredients. Stir to form a soft dough.
Knead with the kneading of the food processor for 7 minutes.
Lightly oil a medium bowl, roll the dough into a ball and place it in the bowl. Cover with a towel and place it in a warm spot to rise until for 1 hour until the dough has doubled.
Rinse well soybean sprouts or mung bean sprouts and drain.
Fry the garlic and onion (white parin oil. Add the remaining vegetables and sauté as well. Deglaze with soy sauce and simmer for 5 minutes.
Once the dough has doubled in size, divide it into 11 balls.
Use a rolling pin to roll the ball into a 4-5 inch round. Brush the top with oil, fold it in half, and transfer it to a piece of parchment paper (I like to to place the parchment paper in the steamer, so I don't have to move it again later). Make sure not to crowd the dough rounds.
Repeat for the remaining pieces of dough. You should have 10-11 rounds.
Let them rest for 10 minutes.
Transfer the parchment rounds to the bamboo steamer if they're not already there. They may not all fit — just work in batches of that's the case.
Layer the tiers in your steamer, place the lid on it, and place it over a large pot of water. Bring the water to a boil and steam the buns for 7 minutes.
Very carefully remove the lid and remove the buns from the steamer.
Fill the vegan Bao Buns with the vegetables.
Serve with green onion, cilantro and more soy sauce.
* The baking paper connects the sticking in the basket. I think that works best. Applying bread paper or the cooking basket with oil does not work and the buns stick to it.