Rinse 1.5 cups (2 rice cooker cups) short-grain Japanese rice under cold water until the water runs mostly clear.
Drain well and add to the rice cooker bowl.
Into the rice, add soy sauce, mirin, sake (or extra mirin), dashi powder (or ½ tsp chicken bouillon)
Gently stir so the seasonings are evenly mixed into the water.
Add 1.25 cups water (or fill to the 2 cup line on your rice cooker).
Spread the mushrooms evenly on top of the rice. Do not mix in. Just layer them.
Place 1 salmon filet on top of the mushrooms.
Lightly season the salmon with salt and pepper.
Close the lid.
Select the White Rice or Mixed/Takikomi setting.Let it cook through the full cycle (about 45–55 minutes, depending on your rice cooker). When the cycle is done, open the lid and gently mix the salmon, mushrooms, and rice together so everything is evenly combined and coated with the seasoned broth.
Top with optional toppings: green onions, togarashi, butter
Serve in a bowl or make onigiri (rice ball) to go. And enjoy!