Grease a pan (mine is ceramic, 24 cm in diameter) with vegetable oil. Line it with the thawed puff pastry, forming a 1.5-2 cm rim. Prick the dough with a fork so it doesn't puff up during baking.

Cut the apples in half, remove the stems and cores. Slice very thinly and arrange them in a circle on the dough - from the edges toward the center.

Make the topping: in a deep bowl, whisk together the egg, sour cream, sugar, vanilla sugar and flour until smooth.

Pour the topping over the pie and spread evenly over the whole surface.

Bake in an oven preheated to 180 °C for 30 minutes.

Brush the finished tart with apricot jam right away. Let it cool completely - and enjoy. Bon appetit!