If using toppings, thinly slice the green onions and finely chop the shiso leaf.

If using a block of tuna, slice it thinly against the grain into bite-sized pieces.

Scoop the cooked rice into a bowl. Make a small well in the center and crack the raw egg into it.

Arrange the sliced tuna over the rice, covering it completely so the rice doesn't show.

Add the toppings, drizzle with soy sauce, and add wasabi to finish.