BBQ Pork Steamed Buns (Banh Bao Nhan Xa Xiu)

BBQ Pork Steamed Buns (Banh Bao Nhan Xa Xiu)
Ingredients:
1 1/2 lb. Barbecued Pork
1/2 cup Barbecued Pork Sauce
1 bag Steamed Buns Flour
1/2 cup Sugar
1 cup Milk (add more as needed)
1 Tbsp. Oil
Small squares Wax Paper
1 Tbsp. Vinegar
Pinch of Corn Starch (Optional)
Mix 1 cup Milk with 1/2 cup Sugar together. In a large bowl, add in the Steamed Buns Flour.  Remember to save about 1/4 cup Flour. 
You can use your hands or a dough mixer to knead the dough. Add in the Sugar Milk slowly. Knead until it is no longer sticky.
Add 1 Tbsp. Oil, continue to knead the dough.
After kneading the dough for 10 minutes. Place it in a bowl, cover with plastic wrap. Let it sit in a warm area for 45 minutes.
After 45 minutes, take out your dough. Divide it into 12 equal pieces. Remember to use the flour you saved to flour your work area and roller.
Take 1 piece of the dough, roll out flat, and add in the fillings. Pinch the top to make the bun, place on wax paper. Put in the steamer.
Repeat until you use up all your dough and fillings. Add in 1 Tbsp. Vinegar to the steamer water.
This will help the buns look whiter. Steam the buns for 20-25 minutes. Remember to serve while hot.
To make the BBQ Pork filling, you need to cut 1 1/2 lb. BBQ Pork into small pieces. 
You can make your own BBQ Pork, I'll have the video link in the description box. or you can click on this link.
In a pan add in 1/2 cup BBQ Pork Sauce. Medium high heat, add in the Pork.  Mix well. 
If it's seems too watery you can add in a pinch of cornstarch to thicken it up.
Remove from heat and set aside.
After 45 minutes, knead the dough again for about 1-2 minutes.  Coat your surface with some flour that you saved.  Roll the dough out and divide it into equal pieces.
You should have about 12 pieces. Take one piece of dough and roll it out flat using a rolling pin. Add in the filling and pinch the top to create a bun. 
Place on a small piece of wax paper. Repeat until you finish using up the dough and filling. Put the buns in the steamer. 
Have your steamer ready, add in 1 Tbsp. Vinegar in the steamer water.  Steam the buns for 20-25 minutes. Remove and serve while hot.