Dough

1. Sift the flour, wheat starch and powdered sugar into a bowl. Add the salt and instant yeast to opposite sides. Start the electric mixer at a low speed and then pour in the soy milk with lesser amount. 
2. Set the setting to #4 and let it run for 6 minutes or knead by hand for 10 minutes, or until soft and smooth. The dough should be soft but not sticky. Cover and rest for 10 minutes.
3. In the meantime, make the paste by blending the red bean paste and black sesame paste together. Divide the paste into 6 portions (about 28g each). 
4. Take the dough and continue to knead it until VERY smooth. Shape it into a circle and then divide the dough into 6 equal pieces (mine were exactly 49g). To easily divide the dough, poke your thumbs in the middle of the circle and  carefully stretch it out to make a donut shape. Cut it into half and then into 3 pieces. Cover the pieces of dough with a damp kitchen cloth. Take one piece of dough, press down with the palm of your hands and then roll it length wise. Fold it up, and roll it out again. Repeat for a total of 5 times. Then roll it out into a circle, as best as you can ensuring the sides are thinner than the middle. The dough should be about 3.5-4 inch in diameter. Add the red bean paste in the middle and pleat it closed. Place them into a steamer basket with 1 inch of space between each bao. Cover and proof the dough for 30-40 minutes. To proof the dough, I microwave a cup of water for 45 seconds and keep them in there with the door half way open. Alternatively, you can add hot water to a pot and then place the steamer basket on top. The time for proofing will depend on your kitchen temperature. To check if proofing is complete, gently press on the dough. It should leave an indentation that spring back slowly. If it springs back quickly, proof longer. If it does not spring back, the dough is over proofed. To try and save over proofed buns, quickly transfer it over into the fridge.
5. Set up your steamer by adding cold water to the pot. Place the steamer back on to the pot over the stove. As soon as you turn on the stove to high heat, set a timer for 15 minutes. Do not open the lid while the buns are steaming. Remove the pot from the heat and keep the baos covered for 5 minutes, and then uncover. Enjoy!