I make this all the time, and there's not much of a recipe, but here's what's on the plate:
My grocery store sells these tuna steaks in the freezer section. They're are typically three individually vacuum sealed tuna steaks in each $7.99 package. Though sometimes there are only two, which makes for kind of a large serving.
I defrost the tuna in cold water in the vacuum sealed package for 40 minutes.
The rest of the plate is:
Fresh diakon radish, grated on the coarse side of a box grater. Soak in cold water for 5 minutes, then squeeze completely dry. Top with hana katsuo (dried bonita fish flakes) and soy sauce.
Sushi rice with furikake.
Soy sauce with wasabe.