Baked Mackerel with White Wine and Mustard

Begin by rinsing the mackerel fillets under cold water. Pat them dry.
Place them in a shallow baking dish.
Mix the dried tarragon, chopped shallot with the wine and vingear and pour over the fish.
Bake in a oven preheated to 200 degrees celcius until the shallots are tender and fish is opaque.
Pour cooking liquor into a small, shallow pan, holding the fish in place with a kitchen slice.
Return the fish to the oven, set the pan over a moderate heat and stir in the mustard.
Add the butter in small chunks.
Whisk lightly until it thickens.
Season with salt, pepper and lemon juice.
Spoon over mackerel and serve straight away.