Grate the lemon zest directly into the sugar and rub into the sugar with your fingers so that it really smells like lemon. That way the lemon sugar infuses the whole pastry.
Cut or grate the butter and place in a bowl along with the remaining ingredients for the shortcrust pastry and knead into a crumbly dough using the dough hook. Put on the work surface and bring together with your hands. Roll out the dough on a floured work surface with a rolling pin or press it directly into the mold. No chilling needed before rolling out, just press the dough into the springform pan, press the edge up the side and prick the base several times with a fork. Put the springform pan in the refrigerator for 30 minutes. You can prepare the pastry ahead of time and put the pastry in the mold and store in the refrigerator.
In the meantime, stir together the quark with sour cream, oil and eggs using the hand mixer. Mix until smooth. Just like with the pastry ,rub the lemon or tangerine peel into the sugar and rub in in with your fingers to make it frangrant. Mix the cornstarch with the citrus flavored sugar and add into the cheesecake batter. Add vanilla and stir everything to a homogeneous mass.
Preheat the oven to 180 ° C / 360F
Put a bowl of water in the oven as it preheats! This provides moisture in the oven and guarantees a German cheesecake without cracks!
Drain the mandarin oranges from the tin and drain very well. Pour the cheese mixture onto the chilled base, smoothen it out and cover with the mandarin oranges (I like spreading out my mandarin oranges and put a few on the pastry before adding the cheesecake batter).
Bake the cake in the preheated oven for an hour. Then turn off the oven and let the cheesecake cool with the door cracked slightly open. Let cool down to room temperature and chill overnight in the fridge.
You can also make this German Cheesecake recipe with apricots, red currants, raspberries, blueberries or peaches!