Cut the schnitzel into strips. Fry briefly in heated fat in a pan and season with salt and pepper. Clean the peppers and cut into strips. Cut the zucchini and mushrooms into slices.
Put the meat and vegetables in a greased baking dish. Mix the sweet cream, sour cream and mustard together and pour over the meat-vegetable mixture.
Cook in the preheated oven for approx. 30 minutes at 200 ° C.