Coarsely dice the fat. Knead flour, 75 g sugar, 1 packet vanillin sugar, fat, 1 egg and salt to a smooth dough. Cover and put in a cool place for about 30 minutes. Roll out to a thickness of approx. 5 mm on a floured work surface. Pour the dough into a greased twist-off tart tin sprinkled with flour.
Press on the dough and cut off the protruding edge. Put the tin in a cool place. Drain mandarins. Stir sour cream, remaining sugar, vanilla sugar, orange fruit and remaining eggs until smooth. Sort the blackberries. Spread the blackberries and mandarins on the shortcrust pastry and pour the custard over it. Bake the tart in the preheated oven (electric: 175 °C/ gas: level 2) for about 1 1/2 hours on the bottom shelf. Remove from the oven, let it cool down for about 15 minutes, remove the mould and let it cool down completely. Whipped cream tastes semi-stiff.
Sort the blackberries. Spread the blackberries and mandarins on the shortcrust pastry and pour the custard over it. Bake the tart in the preheated oven (electric: 175 °C/ gas: level 2) for about 1 1/2 hours on the bottom shelf. Remove from the oven, let it cool down for about 15 minutes, remove the mould and let it cool down completely. Whipped cream tastes semi-stiff. Results in approx. 12 pieces