Onions peel and chop finely. Wash the rosemary, dab dry, pluck the needles and chop. Clean the mushrooms, if necessary wash them briefly and let them drain. Depending on the size, halve or quarter the mushrooms.
Finely dice the bacon.
Peel, wash and halve the potatoes. Heat 2 tablespoons of clarified butter in a large pot. Brown the potatoes all around. Add onions and rosemary and fry briefly. Season with salt and nutmeg.
Deglaze with white wine and stew covered for about 15 minutes.
Meanwhile wash the meat, dab dry and cut into 8 medallions of the same size. Heat 2 tablespoons of clarified butter in a large pan. Fry the meat on each side over high heat for about 2 minutes.
Reduce heat and continue frying for 2-3 minutes, depending on the thickness of the medallions. Season with salt and pepper, remove, wrap in aluminium foil and keep warm.
Fry the bacon and mushrooms in the hot frying fat. Season with salt and pepper. Dust with flour and sauté briefly. Deglaze with stock, bring to the boil and simmer for about 3 minutes. Season to taste with salt, pepper and vinegar.
Arrange the medallions with the mushroom mixture with sauce and the braised potatoes. Small pears and/or cranberries are delicious with them.