This is not so much a recipe as a presentation—one does not actually cook sashimi. I make a Japanese dinner once or twice a month—sashimi, inarizushi, fresh tofu, miso soup, wakame salad, and fresh pickles. This week I had bought two different pieces of Maguro (tuna), some akimi and chutoro.
Note: Some might bring up tataki at this point, but while mostly raw, I would argue that it is cooked and therefore not sashimi.
It did not seem right just to slice the pieces of tuna up and throw them on a plate. That would be very much against the aesthetics of Japanese cuisine—eating should feed both the body and the soul. Looking at the contrasting colors, I decided on my arrangement.