For the veal escalopes with vegetables and mushrooms, preheat the oven to 160 degrees convection. Season the veal escalopes with salt and pepper, sear briefly on both sides in a little butter and place in a frying pan with a lid.
Finely chop the onion, sauté in the remaining gravy, add veal stock or water and gravy cubes, bring to a boil and add to the veal cutlets in the roasting pan.
Close the frying pan with the lid and let it stew in the oven for about 40 minutes. Meanwhile, cut mushrooms and vegetables into pieces. Steam mushrooms in a little butter and season with salt and pepper.
Steam vegetables in vegetable soup or with water and diced vegetables until firm to the bite, season with salt and pepper and toss in a little butter if desired.