Defrost the blackberries. Puree with the cutting stick of the hand mixer and pass through a fine sieve
Mix yoghurt, sugar and vanilla sugar until smooth. Lightly beat the egg whites. Fold in with a whisk. Mix 1/3 of the mixture with the fruit puree. Let both masses freeze separately in the freezer for 3-4 hours. Stir every 30 minutes with a whisk
Pour both sorbets into a piping bag with a perforated nozzle. Quickly squirt the sorbets into pre-cooled dessert glasses and decorate with mint leaves if necessary
Tip: This way you can spray in two colours: Lay the piping bag flat. Fill in one type of sorbet with the dough scraper, carefully put the second type on top. Or simply squirt into the glass one after the other