For the plum liqueur, wash the plums, cut them in half, stone them and put them in a preparation vessel. Add rock candy, cinnamon sticks, star anise and cardamom pods.
Wash the orange while it is hot, cut off the peel generously and also add to the mixing glass. Pour in the grappa and leave to infuse for about 4 weeks.
In between, shake again and again. Then strain and bottle, leave in the bottles for another 4 weeks.