Peel red onions and cut them into rings. Steam in 2 tablespoons of oil for about 5 minutes and salt. Peel and slice the vegetable onions. Steam in the remaining oil for about 8 minutes and season with salt and caraway seeds. Add ham.
Grease a tart tin (26 cm Ø ). Put the contents of the bag of the basic mixture into a bowl and add 1/8 litre of lukewarm water. Knead with the dough hooks of the hand mixer to a smooth dough until the dough comes off the bowl rim. Then knead briefly with your hands. Roll out the dough on a floured work surface to a round plate (30 cm Ø ). Put the dough into the form. Layer the prepared onions in colour. Whisk sour cream and eggs, season with salt and pepper and pour over the onions. Fold the protruding edge of the dough inwards and score it with the handle of a wooden spoon.
Roll out the dough on a floured work surface to a round plate (30 cm Ø ). Put the dough into the form. Layer the prepared onions in colour. Whisk sour cream and eggs, season with salt and pepper and pour over the onions. Fold the protruding edge of the dough inwards and score it with the handle of a wooden spoon. Bake the quiche in a preheated oven (electric: 200 °C/ gas: level 3) on the lowest shelf for approx. 35 minutes