Select ripe, almost black elderberry fruits. Clean the berries and crush them to release the juice in which you're going to be boiling the berries. Make a thick syrup from the sugar and 1 cup of water and put it to boil on medium heat.
Pour in the black elderberries and their juice and let them boil on medium heat until the jam thickens. Finally, mix in the citric acid, if desired. Pour the hot elderberry jam into jars and seal them.
This is a highly healthy and proven treatment for a range of diseases such as cancer, skin irritations, flu and others.