Demi-glace provides an elegant finishing touch to many dishes

A reader of last week’s column asked me to explain “demi-glace,” the sauce served in the duck breast recipe. The term comes from the French word for icing or glaze, and specifically translates as half and mirror. In traditional French cuisine this is a thick, shiny sauce made from an espagnole sauce, stock, herbs and a splash of sherry or Port wine. Once chilled, it will have a slightly gel-like texture.

Unfortunately for many home cooks, the preparation of a proper demi-glace is not an exact science. Each chef has their own approach to the steps in the process as well as the ingredients. For example, Anthony Bourdain’s technique was to roast the bones, then simmer them with herbs, adding wine before the final reduction. Wolfgang Puck uses a pressure cooker to make the stock quickly before the reduction step.

Before we go any further, a few definitions are in order, beginning with the difference between broth and stock. Broth is made from meat or poultry, vegetables and herbs. The meat is removed from the liquid as soon as it is cooked and used in another recipe or chopped and returned to the broth when making a soup. Broth will be more flavorful than plain water as a cooking liquid, which is why it is used in casseroles, stuffing and risotto, just to name a few dishes.

Stock, on the other hand, is made by boiling bones for several hours to release the bone marrow and collagen, which thickens the liquid into a slightly more gelatinous consistency. If you have seen the selections in the soup aisle in the supermarket, you have likely noticed a product called “bone broth.” It is not broth, and should be called stock, because of the use of bones, but the marketing teams prevailed.

The most tedious aspect of making a demi-glace is the lengthy simmering required to reduce it sufficiently. The first ingredient is an espagnole sauce, one of the French “mother” sauces. It begins with a mirepoix, a mixture of finely diced carrots, celery and onions softened in butter. This is dusted with flour and cooked until it becomes a golden roux. After adding a combination of veal stock, tomato puree and a sachet of herbs, the mixture is simmered to reduce by a third.

While this flavorful sauce can be used just as is, often over meat or poultry, it is also used to make a demi-glace by simmering with more veal stock until reduced by half. A spoonful or so of sherry or Port wine will add the proper sheen to your demi-glace, which is best stored in very small portions in the freezer (e.g., freeze in an ice cube tray, then pack cubes into individual zip-top bags and keep frozen).

There are all sorts of shortcuts that will deliver a reasonable version of a demi-glace, but one of the keys to success is not adding any salt until you have the finished sauce. The process of reducing the liquid will serve to highly concentrate the saltiness, and is it always easier to add salt than try fixing an over-salted sauce. In addition to looking up tricks to a speedy demi-glace on the internet, you can find shelf-stable packages in specialty shops. 

I bought the one in the photo at Fresh Market in Rehoboth and chuckled at the mixed messages on the label. The manufacturer, More Than Gourmet, lets the buyer know that their “Classic French Demi-Glace” was “crafted with pride in the USA.” I’ve included their recipe for richly flavored wild mushroom sauce.

Espagnole Sauce

4 T unsalted butter
1/2 onion, finely diced
1 celery stalk, finely diced
1 carrot, finely diced
1/4 C flour
4 C veal stock*
1 T tomato paste
10 peppercorns
1 broken bay leaf

Melt the butter in a heavy saucepan over medium heat. Add vegetables and cook until softened, about 5 minutes. Sprinkle the flour over the vegetables and stir to incorporate. Reduce heat to low and continue cooking, stirring often, until a deep golden color develops, about 10 minutes. Gradually pour in the stock, whisking to eliminate any lumps. Add tomato paste, peppercorns and bay leaf. Bring to a boil over medium, then simmer for 45 minutes, stirring often, until reduced by a third. Line a strainer with cheesecloth and place it over a bowl; pour the sauce through and discard the solids. Store in an airtight container for up to 1 week. *Note: high-quality beef stock may be substituted. Yield: 2 cups.

Classic Demi-Glace

1 sprig thyme
4 stems parsley
1 torn bay leaf
6 whole peppercorns
2 C veal stock
2 C espagnole sauce
2 T dry sherry
salt, to taste

Create a sachet by placing the herbs on a piece of cheesecloth; gather the edges to form a pouch and tie with a piece of string. In a large, heavy saucepan, stir together stock and espagnole sauce over medium heat; add the sachet. Once the mixture boils, reduce heat and simmer to reduce by half, about 55 minutes. Remove the sachet and line a fine mesh sieve with cheesecloth. Set the sieve over a bowl and pour the sauce through to strain. Return to a small saucepan over low. Add the sherry and season to taste with salt. Serve over meat or poultry, or decant into an ice cube tray to freeze and store. Yield: 2 cups.

Wild Mushroom Sauce*

2 T unsalted butter
1 minced shallot
8 oz sliced wild mushrooms
1 C Merlot wine
1 1/2 oz demi-glace
1/4 C heavy cream
salt & pepper, to taste

Melt the butter in a saucepan over medium heat. Add shallots and cook until softened, about 2 minutes. Stir in mushrooms and cook until tender, about 7 minutes. Remove mushrooms to a plate with a slotted spoon; set aside. Add wine to the pan and increase heat; bring to a boil and cook until reduced by half. Reduce heat to low and whisk in demi-glace. Return mushrooms to the pan along with the cream and simmer until heated through, about 2 minutes. Season to taste with salt and pepper; serve over pasta or grilled meat.  *Adapted from More Than Gourmet.