For key visual process photos, refer to the body of the blog post.

Prepare vegetables (if using):

• Place Napa cabbage into a colander and sprinkle 1 teaspoon coarse salt over the top.
• Massage the cabbage for 10 seconds and set aside to drain for about 10 minutes. This is to remove any excess moisture so that the buns do not get soggy.
• After 10 minutes, squeeze the cabbage with your hands and drain away remaining liquid.
• Place the cabbage, mushrooms and leeks (if using) into a food processor and pulse until finely chopped. Remove and place mixture into a large mixing bowl.

Prepare pork meat filling:

• Into a stand mixer bowl fitted with a paddle attachment, add the finely chopped cabbage, mushrooms, and leeks, ground pork, soy sauce, Shaoxing wine, salt, black pepper, sesame oil, sugar, green onion, garlic, ginger and cornstarch.
• Mix all of the ingredients together in one direction until long protein strands appear.
• Place meat mixture into fridge for 20 minutes, or overnight.

Prepare the dough:

• In a bowl, combine yeast, sugar and warm water. Give it a mix and let the yeast activate, a few minutes.
• When the yeast is activated and bubbly, add in flour and salt.
• Knead until the dough comes together. Add in vegetable oil and continue to knead until smooth.
• Turn out dough onto a lightly oiled bowl, cover with plastic wrap, and leave in a warm location until almost doubled in size.
• Once dough has risen, gently deflate and move it over to a workspace dusted with bao flour.
• Divide the dough into 4 quarters and from each quarter, roll it into a log and cut out equal 6 portions. Repeat with the remaining dough.
• Roll each piece of dough into a ball and flatten with your palm.
• Use a rolling pin to roll the dough out into a circle about 3" wide.  Place 1 heaped teaspoon of meat filling into the centre of the dough and pinch and pleat around the dough to seal.
• Place the finished buns onto a lightly greased plate or baking sheet land cover lightly with plastic wrap. Repeat with the remaining dough and meat.

Make the black vinegar dipping sauce:

• In a bowl, stir all the ingredients together. Set aside.

Pan-fry the pork buns:

• Heat a large frying pan with a little bit of vegetable oil over medium heat and place the buns in. Ensure that you leave some space in between the buns for them to expand a little. (You may need to cook in batches, depending on how large your pan is).
• Briefly pan-fry the buns until they are slightly brown, approximately 2 minutes.
• Next, add about ½ C of boiling hot water to the pan and cover with a lid to steam the buns for about 5 minutes, until the meat is fully cooked and the water has evaporated.
• Remove the lid to let any remaining water evaporate and let the bottoms of the buns crisp up slightly and turn golden brown.
• Remove and garnish with sesame seeds and chopped green onions.
• Serve immediately, with black vinegar dipping sauce.