Put the rice in a bowl with cold water and let it soak for about ten minutes, mix it with your fingers so that the grains lose the starch. Then rinse the rice and drain it several times, until the water is transparent: it is a long but necessary operation. Transfer the rice to a saucepan, add the water. Bring the water to a boil over high heat, then lower the heat and let it cook for another 12 minutes, without ever lifting the lid. As soon as all the water has collected, remove the pot from the heat and let it rest in the fridge for 10 minutes. Now prepare the dressing: put the vinegar, sugar and salt in a saucepan and heat until the sugar is completely dissolved. Put the rice in a wooden or plastic bowl, pour the sauce over it and mix with a wooden spoon. Cover with a damp cotton cloth and let it rest at room temperature. Your sushi rice is ready to use.
HOW TO PREPARE URAMAKI
Spread the rice evenly over the entire surface of the nori seaweed. The thickness of the rice must not be very high. Gently lift the seaweed and turn it upside down so that the rice is in contact with the mat and the seaweed faces up. Place the mayonnaise and two avocado wedges on the seaweed, then add the sliced fish. Start rolling. Cut the roll obtained in half and obtain 8 pieces. Transfer to a serving dish and serve your uramaki.
HOW TO PREPARE HOSOMAKI
Spread the rice evenly over the entire surface of the nori seaweed. With your index finger, take a tip of cream cheese and spread it in the center of the rice, so as to create a strip. Then take a strip of salmon and place it in the center of the rice. Then make the roll, and place the hosomaki on a cutting board. Dampen a sharp knife with non-acidulated water, in this way you will not damage the blade. Cut the roll in half, then you get 6 pieces. Accompany the hosomaki with soy sauce and serve.
HOW TO PREPARE NIGIRI
Take about 10-15 grams maximum of sushi rice. By gently pressing give it an oval shape, squeezing the rice in the palm of your hand. With your left hand, grab a slice of tuna or salmon, then lay the rice on it. Press lightly, then flip and press the sides of the fish to shape the nigiri, with thumb and middle finger, so that the two parts are well joined. Proceed with the same operations for all the pieces of tuna or with the slices of salmon. Compose each portion with 1 nigiri of each type of fish.