5 Egg Yolks
2 Cups White Stock (Chicken, Veal, or Fish)
1 Cup of Mushroom Cooking Liquid *
1 Tablespoon Lemon Juice
1 Quart Hot Sauce Velouté
4 Ounces Butter
Whisk together egg yolks, white stock, mushroom cooking liquid, and lemon juice. Add to hot Sauce Velouté and whisk returning to heat. Reduce sauce by one-third, approximately one quart. Whisk 4 ounces cold butter into the sauce.
* Mushroom Cooking Liquid
Is prepared by cooking mushroom for 15 minutes in a covered pot with an equal amount of water. While cultivated button mushrooms work, as with all cooking adding more exotic wild mushroom will make a more flavorful broth.