Close-up of sour cherries, Wikimedia Commons (Nicubunu). 

 Ingredients:

500 grams of fresh sour cherries, pitted

500 grams of sugar

1 half of a lemon

Directions:

Layer cherries and sugar in a saucepan overnight. The following morning, start cooking on low-medium heat. Stir until the sugar melts. Remove the scum from the surface. Cook until the mixture reaches jam consistency. Add the lemon juice 1-2 minutes before you turn the heat off and stir.