Cook and stir to a paste. At this point I add skim milk, about a cup. A cup of soy milk, or a cup of a mixture of nut butter and water coould be substituted. Add a tablespoon or so of nutritional yeast. Flavor to taste, I use salt, pepper, and a little good mustard. I am assuming you know how to work up a fat/flour mixture with added liquid to make a thickened sauce. My version isn't vegan but has the advantage of being relatively low-fat.
