Wash the Juneberries and remove all the stems. Halve the lemon and squeeze out the juice.

Put lemon juice, juneberries and sugar in a saucepan and mix. Bring to a boil.

Purée with a blender, it may be still a bit lumpy.

Now boil for about 20 minutes while stirring constantly. Then test and see if the jam gets firm. If necessary, continue cooking.

Now put in well-cleaned glasses, close with a lid and let cool.