Wash the strawberries, dab dry, clean and chop smaller. Mix with sugar and vanilla sugar in a bowl. Leave to stand for about 1 hour until the juice has formed.
Add the rhubarb juice and wine and let it stand in the refrigerator for about 30 minutes.
Wash the lemon balm, shake dry and pluck the leaves from the stalks. Add to the punch, fill up with Prosecco and spread on glasses. Serve immediately.