Mustard Sauce For Fish - cooking recipe

Ingredients

2 tablespoons butter (no substitutions)
3 tablespoons flour
1/2 teaspoon salt (if fish stock is salty, you might want to reduce or omit salt)
1 dash black pepper
3 cups fish stock (sub chicken stock if you don't have fish stock)
2 tablespoons prepared mustard (dijon is very nice, but any prepared mustard will do)

Preparation

Melt 1 1/2 tablespoons butter in a saucepan; blend in flour and seasonings.
Add fish stock gradually, stirring constantly until thickened then cook an additional three minutes.
Add mustard and remaining butter.
Serve with boiled lutfisk, haddock or cod.