Cut potatoes into bite-sized pieces and soak them in water to remove excess starch. Drain the water. Chop shiso leaves coarsely.

Make a slit in the mentaiko and extract the contents.

Place the potatoes in a microwave-safe container, cover loosely with plastic wrap, and microwave at 600W for 9 minutes. Mash the potatoes while hot, then mix in mentaiko and mayonnaise. Let it cool slightly before adding shiso leaves and pizza cheese.

Place 1/20 of the filling onto each dumpling wrapper. Wet the edges with water and seal them, ensuring the ends form a cross shape. Repeat for all wrappers.