For the tangerine slices, mix egg yolks, sugar, vanilla sugar and water. Add flour and baking powder. Carefully fold in beaten egg whites. Pour the batter onto a coated baking sheet.
Bake in a preheated oven at 200 °C for approx. 15 minutes. Let cool on a rack. Drain the tangerines, reserving the juice. Soak the base with the tangerine juice as needed.
Mix yogurt with sugar and tangerine juice. Soften gelatine according to package instructions, then dissolve and add. Whip the cream until stiff and fold in as well.
Now pour the filling onto the base. Place the drained tangerines on top. Sprinkle with chopped pistachios.