Brush veal tenderloin medallions on both sides with mustard and pepper well (no more salt).
Wrap each piece in a slice of bacon, around the mustard area. Sear with a little clarified butter in a frying pan (with the bacon end first) for about 2 minutes each. Pour the brandy over the top and set on fire, allowing to flash off briefly. Put all pieces in an ovenproof dish and let them stand in the preheated oven at 120° (top/bottom heat) for approx. 10 min. In the meantime, sauté the shallot with a little clarified butter, add the garlic and sauté briefly as well.
Add the mushrooms and deglaze with cream. Simmer the sauce without a lid for about 5 minutes, depending on the desired consistency. Add the drippings from the oven to the sauce. Serve with rösties.
