One of the most important steps to making sushi rice is to clean the rice. Put the rice in a bowl and fill it up with cold water. With your hands, rub in a circular motion. You’ll notice the water is opaque which means it still needs to be cleaned. Strain the water out and repeat until the water is clear. Place the cleaned rice and amount of water required into a rice cooker and allow the rice to cook.
When the rice is done cooking, remove the rice from the rice cooker and place inside a non-metallic bowl. In another bowl, combine rice vinegar, sugar, and salt. Add the vinegar mixture to the rice – you want to do this while the rice is still hot. Take the rice paddle and fold in the rice vinegar. Continue to fold the rice until it has cooled down. If you aren’t going to use it immediately, cover the rice with a wet towel to keep it nice and moist.
Place a pan over medium-high heat. Add all the sliced mushrooms and cook until they reduce in size by half, about 5-10 minutes.
Combine the sugar, sake, rice wine, and soy sauce. Add it to the pan and cook until the liquid has been absorbed completely by the mushrooms, about 5 minutes.
Add the mushrooms to the rice and mix together.
Time to shape the onigiri. Have a small bowl of water next to you because you are going to want to keep your hands moist. Wet your hands and then take a hand full of the rice mixture and begin forming triangle shapes. Put a moderate amount of pressure to make sure they are formed correctly.
