Onigiri are balls of plain rice, with a filling and wrapped with a strip of nori. They are an addition to almost every lunchbox, since they are easy to eat with your hands.
You can choose your filling, but common ones are pickled plum (umeboshi), shredded and salted grilled salmon, or flakes of katsuobushi soaked in a bit of soy sauce.
For the rice, prepare a mixture of water and salt in a bowl. Wet your hands with the mixture and simply take some cooked rice (while hot, so becareful!) and mold it into one hand that has been cupped. Place some filling in the middle, and add another small amount of rice to cover. Then, firmly cup your hands together to form a triangular shape. This takes a lot of practice, since the rice tends to fall apart if you don’t press it enough. Also, your hands should stay a little wet through the ordeal, as rice sticks to dry hands.
Once you’ve completed the rice ball (more like a trianglular ball), wrap it with one strip of nori and serve. If you’re making them the night before and keeping them in a cool place until you serve them, the nori should be added the next day.
Alternatively, you may also add toasted sesame seeds to the rice. If you prefer saltier things, add some more salt to the water mixture.