Wash the strawberries and drain well. Clean, halve or quarter the strawberries and weigh 400 g. Select the raspberries, wash them carefully if necessary and drain them well. Weigh 400 g raspberries as well. Mix fruit, sparkling wine, jam sugar and citric acid in a large pot.
Bring everything to the boil while stirring over high heat. Then let it boil for 3 minutes while stirring further. If necessary, skim off the jam and immediately fill up to the brim into clean, prepared glasses. Close the jars and place them upside down on the lids for about 5 minutes. Turn them over again and let them cool down completely