If you don't plan to fry them right away, you can freeze the filled potstickers until you're ready to cook them. To prevent them from freezing together, freeze them on a sheet pan first. After the outside becomes hard, you can transfer the dumplings to a large freezer bag or other freezer-safe container. They'll keep well in the freezer for up to 3 months. Thaw before making pan fried pork dumplings. Do NOT thaw if you plan to steam or boil them.