How to make
Put the water, sugar and a cinnamon stick to boil into a syrup. Pour the blackcurrants on top, stir and reduce the heat. Allow it to boil until thickened.
From time to time, stir and remove the foam from it. Finally, mix the jam with the citric acid. After 1-2 minutes, remove it from the heat, remove the cinnamon stick, and pour it in dry and warm jars.
Close and turn them upside down.