There are aspects of this sauce that are very similar to Escoffier’s sauce bigarade, which is also an orange-based sauce, but the caramel of this version is a definite variation. When I originally tasted the sauce, it was served with thinly-sliced duck breast, but it goes nicely with grilled pork or chicken, too. Use caution when adding the vinegar and orange juice to the caramel. The caramel will bubble violently for a moment or two when these liquids are added to the hot sugar. Some people remove the saucepan from the heat when adding the liquid.