Heat the oil in a pan. Salt the schnitzel and fry in the pan. Remove the fried schnitzel from the pan, season with pepper and keep warm in the oven at approx. 60 ° C.
Lightly fry the mushrooms, the pepper strips and the chopped garlic in the remaining oil in the pan. Add the stock and tomato paste and let it simmer for about 5 minutes over high heat.
Mix the creme fraîche with the starch, add and simmer for 1 minute. Season with thyme, rosemary, salt and pepper. Pour the sauce over the schnitzel.