In a large terracotta vessel, boil the grape must for 15 hours over a low heat, stirring continuously, until it is reduced by half and becomes a dense syrup. At this point, add the peeled fruit cut into pieces plus the peel of half an orange (without the white pith), and leave to soak for a day changing the water three or four times. Continue the cooking by simmering, to reduce the volume by half again to obtain a very dense sauce. Pour immediately into dry terracotta or glass jars, preheated to avoid them cracking. Keep the jars sealed in a cool dry place that is dark and well-aired. This sauce is excellent with all boiled meats, roasts, “Zampone” and “Cotechino”.