Cut the fillets into serving size portions and place in a large shallow baking pan.
Rub the fish heavy with oil and lightly with the sea salt.
Do this several times while making the sauce.
This I was told is the secret to a well baked fish, massaging the oil and sea salt into the flesh – now who wouldn’t like that.
In a large saucepan, melt butter over medium low heat and slowly stir in 1 tablespoon of flour at a time until incorporated. Stir in the dry seasonings. Slowly stir in the milk and stir constantly until sauce is very thick.
I was told by doing this at a slow pace gives the fish time to rest with the oil and the sauce time to meld with the seasonings. Don’t you just love the ways of ancestral cooking?
Add the vermouth and pour over the fish fillets.
Bake in a preheated 375 degree F. oven for an hour. Sauce should be bubbly and fish opaque but not overly cooked.