Mix the marinade ingredients and marinate the thinly sliced tuna.
Top the grated yamaimo and leek on a bowl of white rice.
Top with the marinated tuna with the marinade, and it's done.
Story Behind this Recipe
I like grated yamaimo and marinated tuna over rice. This is the dish I make when I'm able to obtain cheap lean tuna. There's vinegar in the marinade, so you don't have to make sushi rice. It's easy and quick to prepare.
The tuna is best when it's not over-marinated. When serving to children, cut the tuna into small pieces and serve without wasabi. Your hands are going to itch if you wash off the yamaimo with hot water, so use cold water.