Place the potatoes on a baking tray lined with baking paper. Bake in the preheated oven (electric range: 225 °C/ convection oven: 200 °C/ gas: level 4) for 15-20 minutes until golden brown, turning carefully once.
Wash the chicken filet, dab dry and cut into larger pieces. Heat oil in a pan. Fry the meat for approx. 4 minutes, turning it, and season with salt and pepper. Add 125 ml boiling water.
Add the vegetable mixture without defrosting. Bring to the boil over high heat and cook for approx. 4 minutes, stirring several times. Refine with sour cream, season with salt and pepper. Wash parsley, shake dry and cut into strips.
Sprinkle over the vegetables. Arrange potatoes and vegetables on plates.