Make sushi by picking, gutting and cutting the right fish. Selecting the right fish is based on seasonal and regional factors. Make sure that the fish’s flesh is firm. Start by making the rice and maki-rolls.
Wash the sushi rice, and leave it in the sieve until the water is almost completely clear. Transfer the rice to a heavy bottomed pot, and add water. Bring the pot to a boil, and cover it with a lid. Lower the heat, and cook for 15 minutes.
Turn off the stove, and let the sushi rice steam for an additional 10 minutes. Do not remove the lid during this time. Whisk 4 tablespoons of rice vinegar, 3 tablespoons of granulated sugar and 1 teaspoon of salt together.
When the rice is ready, transfer it to a large bowl, and cover it with the vinegar mixture. Fold the vinegar into the sushi rice. Fan the mixture until the rice cools to room temperature. In a bowl, mix the minced fish with scallions and sesame seeds. Stir to combine.
Dip fingers in a small bowl of water to prevent the rice from sticking to the fingers. Place the nori on the bamboo matt. Wet the fingertips, and place a thin layer of rice nearly three-fourths of the way up the nori.
Lay some negitoro across the edge of the rice, and hook the thumbs under the bamboo mat. Roll the edge up and over the sushi filling. When reaching the end, squeeze the roll from all around. Cut with a sharp knife.