Instructions

1. In a small bowl, stir together ¼ cup plus 1 tablespoon of the vinegar, and the sugar and salt.
2. Into a fine-mesh strainer, pour the rice. Fill a large bowl with cold water, then lower the strainer into it, gently rubbing and tossing the rice to rinse. When the water is milky white, lift the strainer, discard the water, and refill the bowl with fresh, cold water. Repeat this rinsing process until the water remains nearly clear, 2–3 more times. Drain the rice, transfer to a medium pot, add 2¼ cups cold water and set aside at room temperature for 20 minutes.
3. Set the pot over medium-low heat, bring to a simmer, and cook until the water is nearly absorbed, about 15 minutes. Turn the heat down to the lowest setting, cover, and cook until the grains are plump, about 15 minutes. Uncover the pot very quickly (the rice should be completely transparent. If you see any dry spots, sprinkle a little warm water over them and cook 1–2 minutes more.) Remove from the heat and set aside, covered, for 5 minutes.
4. Transfer the rice to a large bowl. Pour over the reserved vinegar mixture and, using a rice paddle or wide wooden spoon, fluff and turn the grains gently, incorporating the seasoning and breaking up any clumps. Push the rice toward one side of the bowl, then insert the paddle into the mound of rice and rapidly move the paddle back and forth, again breaking up any clumps and gradually pushing half of the rice toward the opposite side of the bowl to ensure that the vinegar mixture is evenly absorbed. Using a folded newspaper, fan the rice for 30 seconds, then cover with a damp kitchen towel. Set aside to cool slightly.
5.  In a small bowl, stir together the mayonnaise and chile sauce. In a medium bowl, stir together the remaining vinegar and 1 cup cold water. Wrap a bamboo sushi-rolling mat tightly with plastic wrap and position it so the bamboo strips run parallel to the edge of the work surface closest to you. Top the mat with 1 sheet of nori, shiny-side-down, with the long sides parallel to you. Moisten your hands with the vinegar water and pick up a scant cup of rice, gently forming it into a ball without squeezing. Place the rice ball atop the nori and spread it to cover the nori, leaving a ½-inch wide space along the top of the sheet. Sprinkle the surface of the rice evenly with 1 generous tablespoon of sesame seeds to form an outer coating, then, quickly and confidently, flip the nori over so that the sesame seeds are in contact with the plastic-wrapped mat, the shiny side of the nori is facing up, and the ½-inch border is in line with the bottom of the mat. Smear 2 teaspoons of the chile-mayonnaise mixture evenly over the nori, leaving the uncovered band dry. Arrange the crabmeat along the center of the nori and top with 2 cucumber sticks and 2 avocado slices to form a horizontal line. To roll, use the mat to lift the uncovered strip of nori up over the filling, then continue using the mat to roll the sheet up and away from you, periodically gripping the roll with one hand (over the mat) and pulling back on the other edge of the mat with the other hand to tighten the roll, to form an even log. Remove the mat, drape it over the roll, and press evenly along the roll to firm.
6. Slice the California roll crosswise into 8 even pieces, transfer to a platter, and repeat the process with the remaining ingredients. Serve with wasabi, pickled ginger, and soy sauce, if desired.