Enjoy this with that incredible bottle of full-bodied red wine that you’ve been saving. This is the time.

Serves 6

Ingredients:

For the sauce:

Instructions:

Pat the beef dry with paper towels, then rub it all over with the oil. Season with plenty of salt and pepper. Let stand at room temperature for about 1 hour before roasting.

Twenty minutes before roasting, position a rack in the upper-middle part of the oven and preheat the oven to 425°F. Arrange a wire rack in a shallow roasting pan just large enough to hold the tenderloin. Place the tenderloin on the rack and roast until nicely browned and a thermometer inserted into the thickest part registers 125°F for medium-rare, about 45 minutes. Remove the pan from the oven, transfer the tenderloin to a warm platter, and tent with aluminum foil. Let rest for 20 to 30 minutes while you make the sauce.

In a large skillet over medium heat, melt 2 tablespoons of the butter. Add the shallots and mushrooms and cook, stirring often, until they soften and turn golden brown, about 10 minutes. Add the port and the rosemary sprig and bring to a boil over medium-high heat. Boil until slightly reduced, about 3 minutes. Add the stock and vinegar and continue to boil until the sauce reduces slightly again, about 5 minutes longer. Reduce the heat to low. Remove the rosemary sprig.

mushroom saucemushroom sauce