For the fish pan, cut the defrosted fish fillet into large cubes. In a non-stick pan, sauté the sliced mushrooms and onion. Add the peas.
Fry well until everything is soft and the liquid has boiled away. Add 2 tablespoons of soy sauce and mix well.
Remove everything from the pan and in the remaining residue, stir-fry the diced fish on all sides.
Add the vegetables and mushrooms back to the pan with the fish and season with salt and pepper. Leave to infuse for a little while.
Arrange the fish pan in deep plates