Stone the plums and quarter them. Peel and dice the onions. Dice the peaches. Heat the oil in a large enough pot and sauté the onions until translucent. Add the peeled and finely chopped ginger, the plums, the peaches and the raisins and bring to the boil and simmer for about 5 min.
Deglaze with the balsamic vinegar and simmer for another 60 min on medium-low heat until the mixture thickens a bit.
The gelation can be helped by the juice of a lemon, as it contains natural pectin. If the mixture is still too runny, continue to simmer. Keep stirring and pour the thickened fruit into clean preserving jars.
