Drain the saba miso can and reserve 1 tbsp of the liquid for the sauce.

Finely chop the green onion and shred the shiso leaves.

Mash the hanpen in a plastic bag, then add the saba miso, green onion, sesame oil, and potato starch. Mix thoroughly and cut the corner of the bag to pipe the filling.

Pipe the filling onto dumpling wrappers, moisten the edges with water, fold in half, and seal the ends. Repeat for all wrappers.

Boil water in a pot, cook the dumplings until they float, then transfer them to ice water to cool. Arrange on a serving plate.