It's best to make the sushi vinegar up to a day in advance. Make a batch and store in an empty bottle. It'll keep for 3 months. Be sure to label it clearly so no one drinks it by mistake!
When the rice is cooked, pour on the sushi vinegar while it's still hot, and fold it in using a cut-and-fold motion. Fan with a handheld fan as you mix.
Get the fillings ready as the sushi rice cools. Make the dashimaki tamago and cut into 6 portions lengthwise. Sprinkle the avocado with lemon juice to stop discoloration. Make the wasabi mayonnaise.
Put a sheet of nori seaweed on a sushi rolling mat and spread out the rice evenly, leaving a 2 cm gap on the far side.
Place the lettuce, egg, avocado, salmon and wasabi-mayonnaise on the half close to you.
Roll it up in one go while holding down the fillings, evening out the roll as you go.
Take the sushi rolling mat off. Press both sides of the roll to push in anything that is sticking out with a moistened finger.
Cut the roll up with the seam side down, and it's done.
Story Behind this Recipe
I love this combination in my futomaki.
If you make the sushi vinegar in advance, the flavors blend together and become more tasty. If you cook the rice with a piece of kombu, you don't need to add the kombu based dashi stock to the sushi vinegar. Be careful not to drink the sushi vinegar by mistake when it's stored in the refrigerator! This happened once in our house, so ever since then I've written "Do Not Drink. Sushi Vinegar" on the label with a thick pen.