Baked Ling Cod With Lemon-Garlic Butter Sauce

For the sauce:

Reduce first six sauce ingredients (clam juice, sherry, whole milk, garlic, shallots, bay leaf) by half in a small saucepan.

In a separate saucepan (1-quart minimum) prepare the roux. Heat the first measure of butter in the saucepan on medium heat until it is foamy. Sprinkle in the flour, stirring a couple of minutes with a metal whisk until well mixed (but not browned).

Slowly add the reduced mixture to the roux, stirring quickly to incorporate. When you first add some of the mixture, the roux will bubble up. Just keep adding the mixture and keep whisking to incorporate.

Lower the heat to low. Slowly whisk in the second measure of butter, 2 tablespoons at a time. Add lemon juice, salt, and white pepper. Add some more clam stock if the sauce is too thick.

Note: This makes about twice as much sauce as you'll need for the fish. Refrigerate what is left over and consider using as a topping for potatoes or vegetables.

For the fish:

Arrange an oven rack so that when the fish is on a baking pan in the oven it will be 4 to 5 inches from the heat.

Preheat the oven to 350 degrees F.

Rinse the fillet in cold water, cut into 2 (1-pound) pieces. Remove any bones with fish-bone tweezers or (spotless clean) pliers. Lay out flat in a aluminum foil lined baking pan. Rub some olive oil over both sides of the pieces, enough to coat. Sprinkle both sides with a few shakes of salt and pepper.

Bake for 15 to 20 minutes, until just done. To test, use the tip of a knife to gently cut into the thickest part of the fillet. The fish is done when the fish has just turned from translucent to opaque at the center. Once you pull the fish out of the oven it will continue to cook for a few minutes.