Soak gelatin in water. Wash the lemons with hot water, dry them and rub the peel off. Then squeeze the lemons.
Beat the cream with the vanilla sugar until it is almost stiff. Mix the quark, yoghurt, lemon zest and lemon juice with the sugar. Dissolve the gelatine dripping wet over low heat, add to the quark-yoghurt mixture and stir carefully. Let the cream stiffen slightly and then fold in the whipped cream. Chill for at least 4 hours, preferably overnight.
To serve, cut off the dumplings from the cream and garnish with the fresh berries.