Trim the stems off the shiso leaves. Mince the green onion and ginger.

Remove the small bones and skin from the sanma fillets, then roughly chop them.

On the cutting board with the chopped sanma, add green onion, ginger, and miso paste. Mix and chop until the mixture becomes smooth and uniform.

Divide the mixture into 4 portions and shape them into ovals. Sandwich each portion between two shiso leaves.