In a large mixing bowl, combine 500g of all-purpose flour and 3g of sourdough starter or yeast.

Gradually add 270ml of warm water while stirring with chopsticks or a mixing spoon to form a shaggy mixture.

Once the mixture starts to come together, add 15g of corn oil and knead the dough with your hands until it becomes smooth and elastic. Ensure that there are no dry bits or lumps.

Cover the dough with a lid or plastic wrap and place it in a warm spot to ferment until it doubles in size, usually about 1 hour.

Clean and chop the pork shoulder into small pieces. Then, use a knife to finely chop the meat or pulse it briefly in a food processor, being careful not to over-process. You want to maintain some texture.

In a small bowl, mix together 4g of salt, 4g of chicken essence, 6g of light soy sauce, 8g of dark soy sauce, 2g of five-spice powder,150ml of water and 3g of sugar to create a seasoning sauce.

Pour this seasoning sauce over the chopped pork and mix well with chopsticks, stirring in one direction to make the meat filling sticky and cohesive. This should take about 1 minute.

Continuing to stir until the pork absorbs the moisture and becomes thick and sticky.

Finally, fold in the chopped green onions and mix thoroughly.

Place the filling in the freezer for about 30 minutes to firm up, which will make it easier to wrap later.

Once the dough has doubled in size, transfer it to a clean work surface dusted with flour. Gently punch it down to release any air bubbles.

Divide the dough into 20 equal portions. Roll each portion into a ball.

Take one ball and flatten it into a disc using a rolling pin. Aim for a thicker center and thinner edges, about 3-4mm thick.

Spoon approximately 30g of the filling into the center of each dough disc.

Pinch the edges together to fully encase the filling, ensuring the top is sealed tightly. You can twist the top to secure it further if desired.

Place the filled buns on a piece of parchment paper to prevent sticking, ensuring they have space between them for rising.

Place each bun on a piece of parchment paper. Arrange the buns in a steamer basket, ensuring they have room to expand. Cover with a cloth or lid and let them rise in a warm, humid environment for 15-20 minutes until they have visibly puffed up.

You can create a warm environment by placing the steamer over a pot of warm water or putting it inside an unheated oven.

Fill a pot with enough water and bring it to a boil. Once boiling, carefully place the steamer basket over the pot and cover it with a lid.

Steam the buns for about 15 minutes. Ensure to maintain a strong steam throughout the cooking process for even cooking.

After 15 minutes, turn off the heat but let the buns sit in the steamer for another 3 minutes. This resting period helps to stabilize the buns and prevent them from collapsing.

Carefully remove the lid and the buns from the steamer. Allow them to cool slightly before serving.

Serve the pork buns warm, and enjoy their soft texture and flavorful filling!