In a mixing bowl, dissolve the sugar in water, add yeast and stir.
Cover with a thin cloth and let sit at room temperature or warmer for 15 minutes.
Add flour to a separate mixing bowl. Sift the flour if possible, otherwise sifting is not necessary.
Push a well in the center of the flour and add the sugar/yeast mixture. Add vegetable oil and stir thoroughly.
Knead the dough on a floured surface for 10 minutes. Place the dough in an oiled mixing bowl and cover with a cloth for 3-4 hours.
Place the dough on a floured surface again and place the baking powder on the dough. Knead the baking powder into the dough for 5 minutes.
Divide the dough into small balls, each ball just over 1 inch in diameter.
Break the seitan into small pieces and mix thoroughly with barbecue, chili, and teriyaki sauce.
Flatten each dough ball, add several pieces of seitan, and fold dough edges over the seitan to form a bun. Make sure the buns are sealed around the seitan.
10. Place the buns on the steaming rack of a rice cooker or other steaming device and steam for 20 minutes. If using a rice cooker, the steaming can take place while rice is cooking.