Wash the plums, cut in half, stone and cut into wedges. Wash the oranges with hot water, rub the peel and squeeze the fruit. Now put the plums in a saucepan, mix in the orange peel, the juice, the vinegar, the plum juice, the star anise and the sugar, bring the mixture to the boil and simmer for about 10 minutes. Sprinkle in the pectin and cook for another minute. Now fill the chutney into twist-off glasses, close tightly, turn it upside down for about 5-10 minutes, then turn it over again and the chutney is ready for storage.