Adapted from newengland.com
For the roast:
pounds center-cut beef tenderloin, trimmed
teaspoons kosher salt
teaspoon freshly ground black pepper
Garnish: coarse sea salt such as fleur de sel, rosemary sprigs, roasted shallots
The night before roasting (see Notes), tie up the tenderloin with twine at 1-inch intervals so that it has an even thickness. Sprinkle all over with kosher salt and pepper, set on a wire rack in a roasting pan, cover loosely with plastic wrap, and chill for up to 24 hours. (If you skip this step, simply season the meat before roasting.)
Remove meat from the refrigerator and let sit, covered, at room temperature for an hour before roasting. Preheat your oven to 250° and set a rack to the middle position. Put the whole shallots in the pan (throw in 4 more for a garnish, if you’d like) with the tenderloin and transfer to the oven. Roast until an instant-read thermometer in the center of the tenderloin reads 125°, 1½ to 2 hours. Re
move from oven and let sit at room temperature for 10 minutes. Cut and remove twine. Finely chop the 2 roasted shallots (leave the ones for the garnish whole) and set aside.
Set a large skillet over high heat and add 3 tablespoons of butter. Add the tenderloin and brown all over (including ends), turning as you go, about 1 minute per side. Remove meat from pan and transfer to a serving platter.
A whole tenderloin is a pricey, special occasion cut and it deserves special treatment. Salting the meat the night before you plan to cook it improves the flavor and texture. You don’t have to do this step, but you’ll be glad you did.
For the sauce: Ingredients 3 tablespoons plus 2 tablespoons unsalted butter 2 medium shallots, minced 3 cups beef stock 1 1/4 cups port wine 1 sprig rosemary Instructions Reduce heat to medium-high. Add the remaining 2 tablespoons of butter, along with the minced shallots and the chopped roasted shallots. Cook until fragrant and lightly golden, about 6 minutes, then add the beef stock, port, and rosemary. Bring to a boil, then reduce heat to a simmer and cook sauce, stirring occasionally, until reduced to about 2 cups, 10 to 15 minutes. Pour sauce through a strainer into a gravy boat. Sprinkle the tenderloin with sea salt and garnish the platter with fresh rosemary sprigs and roasted shallots. Serve immediately, cut into 1/2-inch slices, with sauce on the side.