Demi-glace, which comes from the French word for "icing" or "glaze," is a foundation for many other sauces. Beef demi-glace is made by reducing beef stock with wine and sherry until it is thickened and flavourful. The traditional process requires beef bones and vegetables, and can take all day. Some commercial substitutes are available, or you can put together a demi-glace substitute in a few minutes with a few ingredients that are likely already in your pantry.
High-End Demi-Glace Concentrates
Several companies offer demi-glace concentrates that can reconstituted for sauces and other recipes that call for a demi-glace. These concentrates are intensely flavoured, and most recipes require little of the demi-glace to enhance the flavour. High-end concentrates use real beef and veal stock mixed with carrot, onion and celery stocks, red wine, tomato paste, salt and veal and beef fat. They are available online and in gourmet food stores. Most of these concentrates should be refrigerated after opening. The reconstitution ratios vary some between brands, but usually 29.6ml. of the demi-glace concentrate makes 113 to 142gr. of liquid.
Low-End Demi-Glace Concentrates
Low-end demi-glace sauce concentrates cost less than half the price of higher-end concentrates, and the reason is in the ingredient list. The main ingredient in most of these concentrates is modified food starch, followed by maltodextrin, cooked beef fat, partially hydrogenated soybean and/or cottonseed oils, concentrated beef broth, butter oil, salt, dextrose, hydrolyzed corn protein, whey, dried beef extract, tomato powder, autolyzed yeast extract and minute amounts of other ingredients. These lower-end concentrates are mixed with water or other liquid to reconstitute them, and in most cases 28.4gr. of concentrate converts to about 142gr. of liquid. These are also available online.
Though beef stock won't have the depth of flavour or texture that beef demi-glace has, it will work as a substitute in some recipes, though not those that rely on the demi-glace for texture, as in sauces. If you can spend the time cooking the beef stock down to thicken it, it will intensify in flavour and get closer to the texture of demi-glace. If you use beef stock instead of demi-glace, do not add any water called for in the recipe.
Demi-Glace Substitute Recipe
For 1 cup of demi-glace, you can simmer 2 cups of beef broth and 1 tbsp of butter in a pan until the broth is reduced by half. Dissolve 1 tsp of arrowroot or cornstarch in cold water and add to the beef broth, stirring constantly and continuing to simmer until the mixture is thickened. If the mixture is too thick, add sherry or balsamic vinegar 1/8 tsp at a time, stirring after each addition until the sauce is the desired consistency.