Barbecue Pork Buns – Dim Sum

Grease a large bowl with non stick spray.Stir together water, yeast, and sugar for the started in a separate large bowl. Proof mixture by letting it rest in a warm place until its bubbly, about 10 minutes. Stir in the 1 1/3 cup cake flour. Cover and let rise in a warm place until its bubbly, about 1 hour.Whisk together flour, corn starch, baking powder, and salt for the dough. Stir flour mixture and vinegar into starter. Work in the shortening with your hands.Knead dough on a lightly flour surface until its smooth about 5 minutes. Place dough in greased bowl, cover, and let it rise about an hour. Punch down dough and cut into 20 equal pieces. Using your fingers pat each piece of dough into a 3 inch circle.Shape dough circle around the pulled pork filling.Spray 20 two inch squares of parchment paper with nonstick spray. Place 1-2 tablespoons pulled pork filling in center of dough circle . Bring edges of dough over the filling, pinching to seal. Place buns on parchment squares. (**Filled buns can be frozen for up to 1 month**)Arrange buns in steamer, let rise for 30 minutes off heat. (Thaw frozen buns in the fridge.) Steam buns in batches over high heat for 12 minutes. Remove buns from steamer, arrange on a platter & serve.