Preheat oven at 500 F (260 C).

Rehydrate mushroom for 15 minutes. Squeeze water out and mince. Chop long white onion finely.

In a large bowl, thoroughly mix all the ingredients, except seaweed and sesame seeds.

Spread meat mixture flat in a 6"x6" mold or something similar, lined with parchment paper.

Bake in the oven for 20 minutes or until cooked through.

Cool to room temperature. Cut in half, then sprinkle dried green seaweed on one side and sesame seeds on the other. Slice into narrow fan shapes.