Top a Steak Just Like Fancy Restaurants by Jaden | Apr 5, 2007 | Recipes, Sauces/CondimentsA restaurant chef’s secret weapon for mushroom steak sauce is “Demi-Glace,” which is concentrated beef or veal stock that will create a rich, luxurious, meaty flavor that you can’t replicate with any seasoning. Made from scratch demi-glace is a...