Put the ground pork and all the filling ingredients in a bowl and mix well.
Add the chicken soup and mix well. Leave the filling like this for 10 minutes, to let the ground pork absorb lots of soup.
Chop up the leek and cabbage fairly roughly. Sprinkle with 1 teaspoon of salt (not listed in the ingredients) and leave for 10 minutes. Tightly squeeze out the moisture.
Combine the Step 2 meat mixture, finely chopped garlic and ginger, the Step 3 cabbage, and leek.
Mix well, put into a container with a tightly sealing lid, and let it sit for a while in the refrigerator.
While the filling is resting, make the skins. Combine the bread and cake flours. Dissolve the salt in the boiling water, and add this to the flour mixture in 3 batches while mixing well.
When the dough comes together in one ball, place it on a work surface and knead well, while putting your weight into it. Wrap in plastic and rest for 20 minutes at room temperature.
Roll the dough out into thin ropes. Divide into 60 pieces and roll each piece into balls.
Flatten each ball of dough with your palm, and roll the dough out with a rolling pin. Dust generously with flour. Roll the dough out to a 1 mm thickness with a diameter close to 10 cm.
If you don't flour the dough generously, the pieces will get stuck to each other. The thickness is more important than the shape of the skins.
Fill and form the dumplings. Put a generous amount of filling on each skin and then remove any excess. This way, the edge of the skin will be moistened so there's no need to put water on it.
Put the filled dumplings on a shallow tray.
Bring plenty of water to a boil in a wok, and add the gyoza dumplings. They are liable to stick to the bottom of the wok right after they're added, so stir them up gently with a ladle.
When the dumplings float to the surface they are done. Transfer them to servings plates, and serve with the special sauce or ponzu sauce, and cold beer!
Story Behind this Recipe
Boiled gyoza dumplings just have to be made with homemade skins...
Thoroughly squeeze out the moisture from the cabbage and leek. Roll out the dough for the skins very thinly. Aim to make them 1 mm thick. The skins don't have to be perfect circles! The thickness is more important than the shape. Chinese chives aren't added to the filling. If you want some, just add a tiny bit.