Zest and juice lemon.
For the soup: Rinse and chop strawberries. Put 4 tablespoons of strawberries aside for garnish and boil rest with wine, 250 ml of water and 1 sprig of mint. Allow to cool and strain through a cheesecloth.
Soak gelatin in cold water then combine with Grand Marnier and heat until melted. Add to soup mix and season with lemon juice and sugar to taste. Refrigerate.
For the quark foam: Mix quark, lemon zest and vanilla until smooth. Beat egg whites until stiff, sprinkle with sugar, beat again and fold into quark. Cover and chill for about 1 hour.
Place strawberry soup in bowls and top with quark foam. Garnish with remaining strawberries and mint.