Small Sauces: Bigarade

Prepare a gastrique from 6 oz (180 g) sugar and 4 fl oz (120 mL) wine vinegar. Add 8 fl oz (240 mL) orange juice, 3 fl oz (90 mL) lemon juice, 1 qt (960 mL) demi-glace, and, if available, juices from a roast duck. Simmer and reduce to desired consistency. Garnish with blanched julienne of orange zest.