Stir yeast and sugar until the yeast becomes liquid. Put flour, 1/2 teaspoon salt and 3 tablespoons of oil in a bowl. Add 250 ml lukewarm water and yeast. Knead to a smooth dough with the dough hooks of the hand mixer. Cover and leave to rise in a warm place for about 30 minutes.
In the meantime peel onions and cut them into thin rings. Dice bacon. Heat 1 tablespoon of oil in a pan and fry the bacon for 2-3 minutes. Add onions, fry over medium heat for about 5 minutes. Season with pepper and let cool down. Mix eggs, sour cream and chives. Season with salt and pepper. Knead the dough once more, roll out on a floured work surface rectangularly in the size of the baking tray (approx. 40 x 25 cm). Line the baking tray with baking paper. Pour the dough on top.
Mix eggs, sour cream and chives. Season with salt and pepper. Knead the dough once more, roll out on a floured work surface rectangularly in the size of the baking tray (approx. 40 x 25 cm). Line the baking tray with baking paper. Pour the dough on top. Spread the onion and bacon mixture over it and pour the egg sour cream over it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 25-30 minutes
With 8 people: