Sauce Bordelaise
The science
Red wine brings tannin, acidity, and color; reducing it cooks off alcohol and concentrates fruit and structure, while the demi-glace's gelatin balances the wine's astringency into something round. The poached bone marrow — diced, gently warmed so it softens but does not fully melt — adds pockets of rich, beefy fat that punctuate the sauce. The marrow is added at the very end because overheating would render it to grease.
Flavor profile
A reduction of red wine (classically Bordeaux), shallot, thyme, and bay, mounted into demi-glace, finished with poached bone marrow and parsley.
Culinary uses
The definitive sauce for grilled steak — entrecôte à la bordelaise — and other red meats.
Reference notes
Parent: Demi-glace → Espagnole. Region: Bordeaux (wine) hub. Ingredient: bone marrow. Dishes: entrecôte bordelaise.