Ensure the gyoza wrappers are thoroughly thawed before use but remain cold (hard to handle if it reaches room temperature).
Place the mixed filling in the centre and start sealing the wrappers, wetting the ends with some water if required to seal (there are a lot of youtube videos on how to do this).
Place each on baking paper without overlapping and put it into the freezer.
Once partially frozen, you can pack them in freezer bags (I portioned them to 5 per bag, sufficient for each meal).
To consume, bring water to a vigorous boil and drop in the dumplings whilst stirring. The dumplings should be ready when they float but double-check before eating.