Wash the grapes, drain them a little and pluck the berries. Heat the grapes in a saucepan with the prosecco and let them soften. Then grind a little with the potato masher.
Let the mixture cool down a little and then spin Lotte through the liquor to remove the pods and seeds. Measure the juice and add the calculated amount of preserving sugar.
Let it boil for four minutes while stirring according to the instructions.
Pour into prepared jars while still hot, close and place on the lid for about five minutes. Then turn over and let cool. The lid must crack, then the jar has a vacuum.
Note: After it has cooled down, the lid must no longer yield to pressure.