Place the berries in a bowl and allow to thaw. Wash the lemon, grate dry and grate half of the peel thinly. Separate the eggs. Whisk egg yolks, 70 g sugar, vanillin sugar and salt with the whisk of the hand mixer until thick and creamy white (8-10 minutes).
Stir in curd, sour cream, lemon peel and semolina. Beat the egg whites with the whisks of the hand mixer until stiff, adding 50 g sugar. First fold the beaten egg whites into the quark mixture in portions, then loosely fold in the 2/3 of the berries.
Pour the mixture into a greased casserole dish sprinkled with sugar and spread the remaining berries on the surface. Bake in a preheated oven (electric oven: 175 °C/ convection oven: 150 °C/ gas: level 2) for 35-40 minutes.
Remove from the oven and serve immediately. Serve with berry compote or vanilla sauce.