In a large pan (oval if you have), heat up some vegetable oil (test it by putting the tail of the fish in the pan), and start cooking the fish. Flip the fish when the side has a golden colour.

Once both sides are cooked, remove the fish and keep it aside. Remove the fat in the pan. Put the butter in the pan and add the fish back. Manage the heat until the butter gets a nutty colour but DOES NOT burn.

Deglaze the pan with the lemon juice. You should see big bubbles. You can dress the plate and serve with vegetable tagliatelles or steamed potatoes