Caramelized salmon and aromatic soy sauce and butter match very well. Tender mushroom and onion are delicious. This cries out for white rice!
Ootoya restaurant (a cafeteria-style fast food restaurant) serves a dish like this, and its my favorite among salmon dishes. I created this recipe to enjoy a similar taste at home.
At Step 3, you don't need to simmer the salmon for long.
Enjoy Japanese food around the world.