For two to three servings (two to three slices per serving), I crack eggs (three, large) in a bowl and add mirin (1 tbs). I then add the tarako mixture and coarsely crumbled nori (half sheet), beat it using chop sticks to mix well. I also add chopped chives but this is optional.
As usual I use a Japanese square frying pan. On a medium flame, I add vegetable oil (1/2 tbs) and add 2/3 of the egg mixture and gently scramble until it is semi-solid. Using a silicon spatula, I push the egg mixture to one end of the square frying pan to make it into a rectangle shape. If needed, I add more oil in the empty portion of the frying pan and add the remaining egg mixture. Again using the spatula, let the egg mixture flow under the rectangle of the eggs by lifting the rectangle. Wait a few moments until the egg on the bottom is set but the surface is still wet. Start rolling the rectangle of eggs so that the surface is all covered with the last layer of the egg mixture. Make sure the end of the seam is well set (you may have to flip it over several times so that all four surfaces are set). I take it out and wrap it in parchment paper to shape (if need be, further wrap it in a bamboo sushi mat to shape - I did not do this this time) and let it cool. The end result is like the image below, a nice rectangular shaped omelet.