How to make
With a special device or a safety needle, the seeds are removed from the sour cherries.
Place the fruit in a wide and shallow pot, cover them with sugar and leave them overnight.
The next morning, place the pot on the stove on high heat and boil the jam, by removing the thick white foam, that constantly forms on top, with a slotted spoon.
After about 40 minutes, the jam should be ready (a drop of the syrup, is dropped on a cold dry plate and it should not be runny).
Then pour the citric acid, turn off the stove, boil the jam for another minute or two and remove it from the heat.
If there is still some foam, it is completely removed and the sour cherry jam is poured into warmed jars, but it is not closed with caps until it cools down, so that no condensation forms, which can make it candied.
