Wash the chicken filet and dab dry. Season with salt and pepper. Place the fillet on the fat pan of the oven and bake in the preheated oven (electric cooker: 200 °C/ convection oven: not suitable/ gas: level 3) for 15 minutes.
In the meantime peel, wash and slice the potatoes. Heat the oil in a pan. Fry the potatoes for about 20 minutes at medium heat, turning them over. Season with salt, pepper and rosemary.
Remove the chicken filet from the oven and let it cool down a little. Clean and wash spring onions and cut into rings. Mix sour cream, egg yolk and mustard. Season with salt, pepper and sugar. Fold in spring onions.
Cut the bacon into small pieces. Spread the sour cream on the meat. Sprinkle bacon on top and fry for another 10-12 minutes. Arrange the chicken breast with the roast potatoes on a plate. Serve garnished with rosemary and oregano.
A mixed salad tastes good with it.