Omusubi

Bring rice and 2½ cups cold water to a boil in a medium saucepan over medium-high. Reduce heat to low, cover pan, and cook until water is evaporated and rice is tender, 18–20 minutes. Remove from heat and let sit, covered, 10 minutes. Fluff rice with a rice paddle or fork, cover again, and let sit until ready to use.

Melt butter in a nonstick skillet over medium heat. Add all of the mushrooms, season lightly with salt, and cook, stirring occasionally, until slightly softened, about 2 minutes. Reduce heat to medium-low. Add soy sauce, sake, and oil and simmer, tossing occasionally, until liquid is reduced to a glossy sauce that coats mushrooms, about 2 minutes. Stir in shichimi togarashi. Transfer to a small bowl and let cool.

Set up a workstation with a small bowl of water, a small bowl of salt, cooked rice (it should still be warm but cool enough to handle), mushroom mixture, and nori.