For the dough, knead flour, sugar, fat and egg into a smooth dough. Wrap in foil and chill for about 30 minutes. Drain the apricots. Roll out the dough round (approx. 32 cm Ø) and place in a greased tart tin (28 cm Ø). At the same time pull up an approx. 2 cm high edge. Prick the base several times with a fork and pre-bake in a preheated oven (electric range: 200 °C/ gas: level 3) for 15 minutes.
Distribute the apricots unevenly on top. Stir the sour cream, egg, sauce powder, sugar and vanillin sugar until smooth and pour over the apricots. Bake the tart at the same temperature for about 30 minutes. Sprinkle with pistachios. Serve lukewarm or cooled down. Results in approx. 10 pieces