Put both quarks in a bowl. Mix in eggs, 250 g sugar, salt, 1 packet of custard powder and lemon zest one after the other. Grease a springform pan (26 cm Ø) and dust with flour. Put the mixture into the tin and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 50-60 minutes on the lower rack. Let rest for 15 minutes with the oven door open.
Loosen the cake edge with a knife and let it cool down in the pan. For the compote, clean, wash and chop the rhubarb. Wash the strawberries, put one aside for decoration, clean the rest and cut in half. Stir 1 sachet of pudding powder with 100 ml nectar until smooth. Bring 150 ml nectar and 2 tablespoons of sugar to the boil. Add the rhubarb and simmer covered for about 5 minutes. Add the pudding powder and simmer for about 1 minute while stirring. Remove from heat and mix in strawberries. Spread the compote over the cheesecake, leaving the edge free. Chill for 1 hour. Remove the cake from the mould and sprinkle the edge with pistachios.
Add the rhubarb and simmer covered for about 5 minutes. Add the pudding powder and simmer for about 1 minute while stirring. Remove from heat and mix in strawberries. Spread the compote over the cheesecake, leaving the edge free. Chill for 1 hour. Remove the cake from the mould and sprinkle the edge with pistachios. Decorate with the strawberries set aside. Whipped cream tastes good with it
3 hours waiting time