To make siopao dough, make a starter of yeast and flour, add more flour and salt, knead the dough, and let it rise for two hours. The traditional filling for siopao dough is a mixture of seasoned pork and eggs.
In a large mixing bowl, combine 6 cups white flour, 3 teaspoons salt and 6 teaspoons baking powder. Pour 1 envelope active dry yeast into a bowl, add 1 cup warm water, and stir in 1 cup of the flour mixture. Stir thoroughly, cover the bowl, and let the yeast develop for one hour.
Stir 1 cup white sugar into 1/2 cup boiling water, and let it cool to room temperature. Pour the sugar into the yeast, stir it in, and then pour the liquid into the rest of the flour blend. Stir the dough until the ingredients are evenly distributed.
Coat a large, clean bowl with oil or non-stick spray. Cover your work surface with flour, scrape the dough out of its bowl, and knead it for about three minutes. Keep kneading the dough until it is perfectly smooth, and then set it into the greased bowl. Cover the dough with a damp kitchen towel, and let it rise at room temperature for about two hours. When the dough doubles in volume, it is ready for filling.