Mushroom Sauce

Turn and wash half a pound of small mushroom heads (No. 118); put them into a saucepan with the juice of a lemon, and a piece of butter the size of a walnut, some salt and a gill of water. When they are cooked, after three minutes, drain, and put the liquid back into a saucepan with a pint of veloute (No. 415) or espagnole (No. 414), either fat or lean according to its requirements, then reduce and despumate the sauce. Just when ready to serve incorporate into it two ounces of butter and the cooked mushrooms.