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.
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.