Step 1

Rinse the rice in cold water at least 5 times and drain well in a fine-mesh sieve. If using a rice cooker, simply add the rice and cold water to the rice cooker and cook according to the cooker’s instructions. To cook the rice in a pot on the stovetop, place the rice in a pot with a tight-fitting lid. Add the cold water and bring to a boil. Reduce heat to a very low simmer, cover the pot, and simmer for about 20 minutes, until all of the liquid is absorbed and the rice is tender.

Step 2

If using the sushi rice seasoning, while the rice is cooking, combine the vinegar, sugar, and salt in a small saucepan and heat over medium heat, stirring, just until the sugar is dissolved. When the rice is finished cooking, stir the vinegar mixture into it until well combined.

Step 3

Transfer the rice from the rice cooker or cooking pot to a large bowl and let cool until it is cool enough to handle.

Step 4

Shape your onigiri while the rice is still warm. If using a mold, wet the inside of the mold and, using wet hands, fill it about halfway with rice. Make an indentation in the middle of the rice with your thumb and add your filling, about a tablespoon or so. Add more rice on top to fill the mold. Place the top half of the mold on top and press down gently. Remove the top of the mold and invert the bottom half over a plate. Press down on the button in the middle to help the onigiri slide out. Wet the inside of the mold again and repeat the process until you have used up all of your rice and filling or have made the desired number of onigiri.

Step 5

If shaping the onigiri by hand, use wet hands and shape into a ball, make an indentation in the middle, fill with about 1 tablespoon of filling, and close up the hole with a bit more rice. Leave it in a ball shape, or use your hands to form it into a triangular shape, if desired.

Step 6

If using individually-wrapped onigiri wrappers, leave the plastic wrap on them and wrap them around your rice balls. If using regular nori sheets cut into strips, wrap in plastic wrap. Onigiri can be stored at room temperature for several hours. If you wish to store them longer than that, store in the refrigerator and bring to room temperature before serving.

Step 7

To serve, remove the plastic wrap from the nori wrapper, if necessary, and wrap the onigiri in the nori or simply remove the plastic wrap and serve at room temperature.