2 lb. unsalted butter
1 onion, chopped fine
10 peppercorns, crushed
1/2 cup dry red wine
1/4 tsp. dried thyme
1-1/2 cup demi-glace sauce

Heat the butter in a small frying pan over medium heat. Add the onion until soft. Add peppercorns, wine and thyme, until most of the liquid has evaporated. Stir in the demi-glace sauce and cook until the sauce is reduced to 1/3. Strain, taste and adjust seasonings.