Cook the BBQ pork filling: (best done ahead of time)

• Sauté the onions and garlic until translucent, about 3-4 minutes over medium heat.
• Add in the diced BBQ pork and continue to sauté until the pork is heated through.
• Next, add in 5-spice powder, light soy sauce, sugar, Chinese rose wine, hoisin sauce, and ketchup.
• Prepare the cornstarch and flour slurry by adding 1 teaspoon cornstarch and 1 teaspoon flour into a small bowl with 5-6 tablespoon water. Mix with a spoon until the starch and flour dissolves.
• Pour the slurry into the pot and stir to coat the BBQ pork mixture. Lower the heat.
• The mixture will begin to thicken and become glossy. Add in ½ teaspoon sesame oil and stir to combine.
• Remove the BBQ pork filling and transfer to a bowl. Cover with a lid and let cool.
• Refrigerate the pork filling for at least 4-6 hours, or overnight.

Make the dough for the buns:

Make the tangzhong:

• In a small saucepot, add in flour and water.
• Whisk over low-medium heat for about 5 minutes, until thickened, like a paste. Remove from heat and let cool to room temperature.

Make the dough:

• Pour the warmed milk into a bowl, add in the sugar and yeast.
• Give it a stir and let the yeast activate and bubble.
• In a bowl of a stand mixer fitted with a dough hook, add in the flour, about 75% of the egg (remember to save some for the eggwash later), oil and sea salt.
• Start the mixer on low and pour in the activated yeast and milk. Add in the cooled tangzhong.
• Knead until the dough starts to come together and forms a smooth and shiny ball, about 7-8 minutes of kneading.
• Put the dough into a lightly greased bowl and cover with plastic wrap. Place in a warm location and let the dough double in size (approximately 60-90 mins, depending on how warm your kitchen is).
• Prepare a baking sheet with parchment paper. Set aside.
• Once the dough has risen, deflate the dough and divide into equal portions, about 62g each.
• Divide the pork filling into 8 equal portions, about 55g each and place onto a plate.
• Tip: Use a large ice cream scooper to portion out the filling, and that way you can transfer the filling onto the bun easily.
• Roll out each portion of dough into a round disc, with the outer edges slightly thinner than the centre.
• Place the BBQ pork filling in the centre of the dough, being careful not to get any sauce near the edges. Any sauce or moisture will prevent the dough from sealing properly.
• Carefully gather the edges of the dough and pleat to seal the bun.
• Place the bun seam-side down onto a piece of parchment paper.
• Repeat with the remaining buns.
• Cover the buns loosely with plastic wrap and leave to rest for about 30 minutes in a warm location, or until fully proofed.

Bake the buns:

• Before the end of the proofing time, preheat the oven to 375°F.
• Use a brush the tops of the buns with the remaining beaten egg.
• If you wish, you can sprinkle the tops with sesame seeds, or omit like I've done here.
• Bake the buns at 375°F for about 15-17 minutes.

Make the sugar glaze:

• Prepare the sugar glaze by mixing 1 tablespoon sugar with 1 tablespoon hot water until the sugar is dissolved.
• Remove the buns from the oven. Brush the tops with the sugar glaze and return the buns into the oven for 1-2 minutes.
• Remove the bun from the oven and let cool.