For six to eight persons.
For the beef
For the Mustard Sauce
In a bowl combine the olive oil, rosemary, fennel seed, salt and pepper. Stir to make a paste.
Pat the beef dry with paper towels and rub the paste all over the surface of the meat. If ncecessary, tie the roast at 1 1/2 inch intervals and then place in the fridge - the roast can be seasoned and placed in the fridge for up to four hours.
Place the oven rack in the centre and heat the oven to 375 (F).
Place the roast on a rack in a shallow roasting pan. Roast until an instand-read thermometer inserted in the center reads 120 (F) for rare, 125 to 130 (F) for medium rare, or 135 (F) for medium, 40 to 50 minutes.
To make the sauce, while together the crème fraîche, mustard and lemon juice. Season lightly with salt to taste. Crème fraîche, if not available can be replaced with a combination of sour cream and full cream as a substitute.
I first made this dish for a December pre-Christmas Dinner party. It went over very well. My slices were not thick as the piece of tenderloin I had was much wider. Cut yours according to what you have.