The reward for making stock and reducing it for hours is this potent source of umami that takes up very little space and keeps for months in the refrigerator or freezer. Use to add flavor and body to sauces, braises, and soups.

Prepare:

Strain and skim any fat from the stock. Transfer to a medium saucepan and set over medium-high heat. Allow the stock to simmer vigorously, skimming off any foam. When the stock begins to thicken, reduce the heat to avoid burning. For demi-glace, the reduction is complete when it is the consistency of a light syrup. For glaze, the mixture should coat the back of a spoon and be of a honey-like consistency. Depending on the amount of gelatin in the stock and the size of the pot, this can take anywhere from 2 to 4 hours for the given amount of stock. Once the desired consistency has been reached, remove from the heat, transfer to a bowl or other container, and let cool. Once solidified, demi-glace will jiggle a bit like an aspic or gelatin dessert (glaze will be stouter and feel rubbery to the touch). Cover and refrigerate or cut into small squares and freeze in a zip-top freezer bag.