Select the currants, wash them and remove them from the panicles with a fork (weigh 800 g of berries). Chop ginger very finely. Mix with berries, jam sugar and apple juice in a large pot.
Leave to infuse for about 30 minutes.
Bring the berry mix to the boil while stirring constantly and boil for approx. 4 minutes until it becomes bubbly. Immediately pour into hot-rinsed glasses with twist-off lids. Close the jars and place them on the lid for about 5 minutes.