The delicate of this luxurious sauce makes it perfect for creaming poultry, eggs, or elegant edibles such as sweetbreads or oysters.
Melt the butter in a large heavy saucepan over medium heat. Whisk in the flour and cook for 3 minutes, then stir into the hot stock. Add the peppercorns and mushrooms and simmer gently over low heat at least 30 minutes. Strain through a sieve lined with cheesecloth and season to taste with slat and pepper.
Yield: About 2 cups of sauce.
From The Complete Book Of Sauces by Sallie Y Williams