In a mixing bowl, combine the warm water, instant yeast, and sugar. Let it sit for about 5-10 minutes until it becomes frothy.
In a separate bowl, whisk together the all-purpose flour, salt, and baking powder.
Once the yeast mixture is frothy, add it to the bowl of dry ingredients along with the cooking oil. Mix until a shaggy dough forms.
Transfer the dough onto a lightly floured surface. Knead the dough for about 10 minutes until it is smooth and elastic. Add more flour if too sticky.
Place the kneaded dough into a lightly oiled bowl. Cover and let rise in a warm place for about 1 hour, or until doubled in size.
Punch down the dough to release air. Divide into 14 equal pieces. Roll each into a ball and flatten with your palm. Roll out to 4 inches diameter circles.
Add desired filling to the center of each circle. Gather edges and pinch to seal. Place buns seam side down on parchment squares.
Cover buns with a damp cloth and let rise for another 30 minutes.
Bring water to a boil in steamer. Place buns on parchment in steamer basket with space between. Cover and steam for 15-20 minutes.
Remove buns from steamer and let cool slightly before serving. Enjoy with soy sauce, chili oil, or favorite dipping sauce.