Select raspberries, wash if necessary. Strawberries wash, clean. Weigh 1000 g berries. Mix raspberries, strawberries and jam sugar in a large pot. Bring to the boil over high heat while stirring constantly.
Then boil for at least 3 minutes until bubbly. Stir in Grappa. Immediately fill jam into prepared twist-off jars and close them. Let cool upside down
Shelf life 6-9 months