To make the filling, finely chop 1 scallion after removing the root. Also finely chop 5 stalks of Chinese chives after removing the bottoms. FInely chop 4 medium size Chinese cabbage leaves as well as fully hydrated shiitake mushrooms. Also, finely chop a small piece of bamboo shoot. See the accompanying picture as a reference for suitable portion size.
Season the ground pork by adding 1/3 tsp each of salt and black pepper, 1 tbsp each of sake and soy sauce, and mix together.
Add the chopped vegetables and shiitake mushrooms and mix everything well. Then add 3 tbsp of sesame oil and mix well again.
Cover the filling with plastic wrap, and then let it rest in a refrigerator for at least 1 hour.
Place 1 dumpling wrapper in the palm of your hand, making sure that your hands are completely dry. Carefully wet just the edge of the wrapper with a small amount of water with your finger.
Place a little more than 1 tsp of the filling in the center of the wrapper, and gently fold over and press together to seal just the center of the wrapper.
Then on each side, make and squeeze 3 pleats to make a gyoza dumpling, making sure all the edges are tightly closed.
Sprinkle katakuriko, Japanese potato starch powder, on a shallow cooking tray and place the each dumpling on it. The katakuriko prevents the dumpling from sticking to the tray.
To make the wings for 5 gyoza, mix together 1/4 cup of water and 1/3 tsp each of all-purpose flour and katakuriko powder.
Add 1 tbsp of oil to a frying pan. Add the 5 gyoza to the pan, and turn the heat to medium high, leaving them to cook uncovered for 3 minutes.
Then turn the heat off and check that the bottom of the gyoza are nicely browned.
Once the bottom of the gyoza is nicely browned, pour in the water and flour mixture. Make sure that the liquid fully covers the bottom of the pan.
Cover with a lid, then turn on the heat to medium, and cook for another few minutes.
After 2 - 3 minutes, open the lid and check that the liquid mixture has not dried out. Once the dumpling pleats have become translucent, and the filling is fully cooked, uncover and continue cooking until the liquid has almost evaporated.
Wing-shapes start to form around the gyoza dumplings. Then carefully pour about 1 tbsp of sesame oil around the gyoza.
Keep on cooking for another 1 - 2 minutes uncovered, until the oil is absorbed.
When ready, turn off the heat, carefully flip the gyoza from the pan onto a slightly smaller plate. It's ready! We hope you enjoy your "TOKYO FLAVORS, NEW YORK STYLE" meal! Itadakimasu!