In a large mixing bowl, add all pork filling ingredients and mix the ingredients with your hands until evenly distributed. The mixture is ready when the meat starts to feel “sticky”.
Have a small bowl of water ready nearby. Dust a cookie sheet with cornstarch and arrange the groza wrappers neatly in several rows. Place a heaping tablespoon of pork filling in the middle of each gyoza wrapper. Place the gyoza wrapper in the palm of your non-dominant hand. Moisten a finger with water and trace your finger around the edge of the wrapper. Gently fold the wrapper in half and pinch the middle of the wrapper to seal the edge. Working one side at a time from centre to the edge, gently pleat the top of the wrapper and press down to seal the edge. Repeat for the other side of the wrapper, you should end up with 2 to 3 pleats per side. Set gyoza aside and repeat for remaining gyoza until all the filling is used.
Coat a large frying pan with oil and place over medium-high heat. When the oil starts to smoke, arrange the gyoza in the frying pan flat side down about 1 inch apart. Cook for about 3 to 5 minutes, until the bottom is golden brown. Add about 1 tablespoon of water to the pan and cover, steam the gyoza for another 3 to 5 minutes until cooked through.
While the gyoza cooks, prepare the tare dipping sauce. In a small bowl, add soy sauce, hot sesame oil and vinegar. Garnish with chives, sesame seeds and red pepper flakes for some extra heat.
Serve the gyoza on a plate, browned side up, with tare dipping sauce and optional sides.
When folding gyoza, cover remaining stack of gyoza wrappers with a damp towel to prevent from drying out.
Freeze remaining gyoza for later use. Place gyoza on a silicone lined baking sheet and place in freezer. When frozen through, transfer gyoza into freezer bags. Do not defrost gyoza, cook from frozen.
Recipe from https://emicooks.com/japanese-pork-gyoza/