Cook the rice according to your rice cooker or if you don’t have a rice cooker, follow the instructions here. *5
Transfer the cooked rice to a separate bowl to cool it down. I used a Japanese wooden bowl*6 for sushi making.
Prepare all the fillings that you are going to use and set aside. *7 see some suggestions
I used Umeboshi (pickled plum), Okaka (bonito flakes), and Tuna. For Umeboshi, deseed the plums then divide the flesh into three chunks. For Okaka, place bonito flakes into a small mixing bowl and combine with soy sauce and mirin. For Tuna, drain the brine or olive oil and mix with 1 tbs mayonnaise.
Prepare seaweed sheet (nori). ＊8
Place cling wrap over a rice bowl.
Place 1/6 of the cooked rice ( 3/4 cup or 120g) over the centre of the cling wrap and make a well.
Put about 1tsp of umeboshi (or any fillings of your choice) on the centre of the rice then cover with the rice around.
Wrap the cling wrap over the rice and squeeze and mould the rice into a triangle shape with your hands.
Remove the cling wrap and cover the bottom of the rice triangle with a nori sheet and set aside.
Repeat the same steps as above to use rest of the rice with other fillings that you prepared.
Cooking rice is not included in the cooking time.*1 Preferably Japonica Short grain rice such as "koshihikari" or the rice packet labeled "sushi rice". *2 If you are going to make the special onigiri film, you need 3 nori sheets and cut them in half length wise. Nori sheets are usually 7.5 x 8 inch (19 x 20 cm). Cut them into 3.75 x 8 inch (9.5 x 20 cm) in size. *3 You do not need all of this amount. Left over can be used for Sushi rolls or tuna sandwich. *4 Need approximately 1/4 of the piece ( weighed 5 oz /150 g). Left over can be used for Obento filling or Sushi rolls. *5 How to cook rice without a rice cooker*6 There are special wooden containers called “ohitsu” to keep cooked rice in Japan. Once the rice is cooked, the rice needs to be loosened with a wooden spatula then keep it in the wooden container. Because the wooden container will absorb the extra moisture and make the cooked rice plump but not soggy.*7 Pickled plum, bonito flakes seasoned with soy sauce and mirin, tuna flavoured with mayonnaise, kelp simmered in soy sauce (tsukudani), teriyaki chicken, yakiniku (grilled beef) etc. Fillings in the ingredients list are the ones I used for this rice balls recipe. *8 In Japan or from Japanese grocery stores, you can find nori already cut to the size of a regular Onigiri. If you can only get nori sheets for making sushi, I usually briefly roast it under a low oven or grill setting, and then cut out into 8 strips.Also If you are going to take the rice balls for lunch and keep the nori sheets fresh, follow the wrapping instructions given in the above post.