Rinse the rice in cool water until the water runs very clear. Drain well.
Pour the water into a heavy-bottomed saucepan (use one with a tight-fitting lid). Bring the water to a boil over medium-high heat (see note). As soon as the water is boiling, reduce the heat to low-medium. Stir in the rice. Cover with the lid. Adjust the heat as needed to maintain a low simmer in the pan. Simmer the rice until all of the liquid is absorbed and the rice is tender, 16 to 18 minutes.
While the rice cooks, heat the rice vinegar, sugar, and salt in a small saucepan or in the microwave, stirring occasionally, until the sugar and salt dissolve. Set aside.
When the rice is done cooking, transfer it to a mixing bowl. Pour the seasoned vinegar evenly over the top. Use a large spoon or flexible spatula to gently fold the vinegar into the rice, being careful not to mash the rice, until it is evenly seasoned. Cover the rice with a clean dish towel and set it aside until it is cool enough to handle.
Prepare and set out all of your sushi filling ingredients - nori, vegetables, crunchy items, and sauces. You’ll also need a small bowl of water and parchment paper or a sushi mat.
Assemble your sushi rolls one at a time by setting a piece of nori out on a sushi mat or piece of parchment paper. Place a piece of nori with the shiny side down on the mat or parchment paper. Spread a thin layer of sushi rice on the lower 2/3 of the nori, leaving the upper 1/3 free. Add fillings in a single row across the center of the rice.
Now roll! Starting with the side closest to you and using the parchment paper for leverage, roll the nori into a compact log. The rice should completely enclose the filling. When you reach the end, dampen your finger with water and run it along the end of the nori, pressing to seal.
Slice the rolls into 1 ½-inch rounds. Serve with soy sauce / Tamari, wasabi, and pickled ginger on the side.