Add the package of yeast to the 1/2 C warm water. Let sit until bubbling.
Combine the flour, sugar and baking powder in a large bowl.
Slowly whisk in the warm milk and canola oil until the dough begins to come together.
Transfer to a well floured counter top and knead until smooth and elastic (about 5-10 minutes). OR Place in stand mixer with dough hook. Turn on medium for about 5 minutes, until the dough is smooth and elastic.
Lightly oil a large mixing bowl and place the dough ball inside. Rub a small amount of oil over entire ball. Cover with plastic wrap and set aside to rest and rise for 1 hour.
For the filling, toss the pork with the chili paste, onion powder, granulated garlic and soy sauce.
Heat 2 T canola oil over high heat in a large saucepan, then add the pork mixture.
Once meat is almost cooked through, add fish sauce, brown sugar, chicken stock and cornstarch.
Reduce until sauce has thickened slightly. Add the napa cabbage and cilantro and sauté until soft.
Once the dough is ready, roll it into a long rope. Cut the rope into 12 equal portions, rolling each into its own ball.
For the buns, roll one portion of dough out into a 4" circle. Place one heaping tablespoon of filling in the center, then pinch the edges together at the top.
Set on parchment paper and cover lightly with a clean towel while you finish filling the others.
To steam the buns, coat the bottom of a steaming rack with cabbage leaves and bring water to a boil.
Steam the buns a few at a time until dough is cooked through, about 10-15 minutes. Be sure not to crowd the steamer, as the buns will stick together.