First, defrost the raspberries and strawberries. You can also take fresh fruit, but wash it beforehand. Then puree the fruit with the lemon juice of 1/4 lemon. If you don`t want any seeds, you should pass everything through a sieve or puree longer.
Pour the sparkling wine (well chilled if consumed immediately) into a punch bowl. Add the fruit pulp and stir well. If it takes longer to serve, place the bowl in the refrigerator.