Prepare the Filling: In a bowl, combine the ground pork, light soy sauce, dark soy sauce, oyster sauce, salt, chicken concentrate, and spices. Stir vigorously in one direction until the meat becomes sticky and paste-like.
Stir in the vegetable oil and sesame oil to lock in moisture. Fold in the chopped scallions. Cover and refrigerate while you make the dough (cold filling is easier to wrap).
Activate Yeast: In a bowl containing the 400g warm water, add the sugar and instant yeast. Stir and let sit for 1 minute.
Mix Dough: In a large mixing bowl, whisk together the flour and baking powder. Pour in the yeast water mixture. Use chopsticks or a spatula to stir until no dry flour remains (approx 1-2 mins). The dough will be very wet and sticky. Do not knead.
Ferment: Cover the bowl securely. Let it rise in a warm place until tripled in size. The dough should look full of bubbles and honeycomb-like inside.
Assemble: Generously oil your hands and your work surface. Do not use flour. Gently pull a piece of dough (about 90g) without deflating it too much. Flatten it in your palm.
Place a large scoop of filling (approx 65g) in the center. Pull the edges of the dough up and over the filling to the center, pinching tightly to seal. Place seam-side down on the oiled surface.
Pan Fry: Preheat a skillet with a generous amount of oil over medium-low heat. Place the pies in the pan and gently press them flat with oiled fingers.
Cover the pan and fry for about 3 minutes until the bottom is golden brown.
Flip the pies. Fry uncovered for another 3 minutes or until golden on both sides and the pork is cooked through (internal temp 160°F).