Mix the plum and apple pieces with honey, lemon juice, and raw cane sugar and let the juice steep overnight.
Heat together with the remaining ingredients while stirring and let simmer for 3 - 5 minutes. Make a gelling test and, if necessary, add a little lemon juice.
Pour into hot rinsed glasses (full to the brim), close tightly with the twist-off lids, turn upside down and allow to cool.