This brown reduction can be made using any stock you have available to you and some time. Originating in France, Demi-glace is a base used to finish many meat dishes, or use to build a more robust and flavorful sauce to toss some otherwise bland vegetables in.
TimeAbout 4 hours
Gently bring stock to a simmer for about 2 hours - checking frequently until reduced by half.
When the stock has reduced by half, transfer to the saucepan and bring to a simmer for about 2 hours — again, checking frequently.
Reduce by three quarters until there is about 2 cups left. If it over-reduces, it may scorch so be sure to keep an eye on it.
Strain through a colander lined with cheesecloth into a heat-resistant container and refrigerate until cool.
Use immediately or freeze indefinitely — ideally in an ice cube tray for easy portioning.