Add the sushi rice to a fine-mesh strainer. Rinse under cold running water, gently stirring the grains with your fingers, until the water runs almost clear.

Drain the rice well and transfer it to a medium saucepan. Add 2½ cups water.

Bring the rice to a gentle boil over medium-high heat. Reduce the heat to low, cover, and cook for 15 minutes without lifting the lid.

Remove the saucepan from the heat and leave it covered for 10 minutes. The trapped steam will finish cooking the rice.

While the rice rests, combine the rice vinegar, sugar, and salt in a small bowl. Stir until the sugar and salt dissolve. Warm the mixture briefly when needed, but do not boil it.

Transfer the warm rice to a wide bowl. Pour the vinegar mixture evenly over it and gently fold with a rice paddle or wooden spoon. Avoid mashing the grains.

Line a 9×13-inch baking dish with parchment paper. Transfer the seasoned rice to the dish and spread it into an even layer about ½ inch thick.

Place another sheet of parchment paper over the rice. Press down firmly with your hands, the bottom of a glass, or a flat measuring cup so the grains hold together.

Refrigerate the pressed rice for at least 2 hours, or overnight, until completely cold and firm.

Lift the chilled rice from the dish using the parchment paper. Cut it into approximately 18 evenly sized rectangles.

Heat enough canola oil to lightly cover the bottom of a large nonstick skillet over medium-high heat.

Add the rice pieces in a single layer without crowding the pan. Fry for 3 to 4 minutes, or until the bottoms are deeply golden and release easily from the skillet.

Carefully turn each piece and fry the second side for another 3 to 4 minutes.

Transfer the crispy rice to paper towels or a wire rack. Repeat with the remaining pieces, adding more oil when needed.

Serve immediately while warm and crispy, either plain or topped with avocado, spicy tuna, salmon, sesame seeds, or sliced green onion.