Warning: this method may upset some sauce purists. But this is the way I learned it, and a subsequent taste testing with a classically prepared version decided what I thought instinctively when I saw the classic method as laid out by the master, Escoffier:
- Make sauce espagnole by sweating mirepoix in fat, preferably clarified butter. Add flour and cook to make a brown roux, stir in tomato paste to add colour and rich flavour. Add brown veal stock and boil, then reduce to a SLOW simmer for 1-1.5 hours, allowing the sauce to reduce. Skim occasionally to remove impurities. Strain through a conical strainer lined with several layers of cheesecloth.
- Combine 1 part sauce espagnole and 1 part brown veal stock and reduce by half.
Voilà, your demi-glace is ready! It should be lump free, a glossy dark brown, and thick without being pasty. (Yawn…)
Compare that with what Chef P taught us:
- Reduce a high-quality brown stock by half.
Voilà, your demi-glace is ready! It is ALWAYS lump free, glossy dark brown, and thick enough to coat the back of a spoon. It makes a contemporary, rich flavourful base with a lighter mouth-feel than the version above.
What are your instincts saying?
I used some of my demi to make this pink peppercorn diablo sauce — add crushed black & pink peppercorns and minced shallot to white wine. Reduce by two-thirds over medium-high; strain. Combine reduction with demi-glace and reduce to coat the back of a spoon. Remove from heat, season with s+p and cayenne to taste and finish with a pat of butter for some last minute thickening and gloss. I served it over grilled lamb chops, with braised endive and horseradish mash.
Then, in what only be called a HERCULEAN effort at the end of a very long day of stock making, I reduced the remaining demi-glace by half again, resulting in a lustrous, gelatin-packed glace de viande. I covered it very tightly and put it in the fridge to await it’s final fate. I think it knows what’s coming, though; it literally quivers with fear when I open the door.