Put the berries, vanilla stick and 500 g of the sugar in a large saucepan and slowly bring to the boil. Let simmer for 1 minute. Add the rest of the sugar, bring to the boil again and simmer for about 3 minutes, make a gelation test.
Pour the jam boiling hot into the prepared glasses, turn them upside down for 5 minutes.
Makes approx. 7 glasses of 250 ml each. Shelf life: approx. 1 year