Last night, after a few glasses of wine I managed to knock up a killer sauce to go with some chicken breasts that had been cooked sous vide (4 hours @ 63.5 deg C - perfectly succulent). Unfortunately, I didn't take photos, or write down exactly how I did it, but it started off with lightly fried shallots, chicken stock, Dijon mustard and carob syrup, thickened with cream and the juice of half a lemon to sharpen it up a bit. I am under instruction to make it again, so next time will record it, as it really was very good indeed. I suspect it might also work with steak.