From The New York Times.
(4-pound) beef tenderloin, trimmed and tied
1 tablespoon kosher salt, more to taste
1 teaspoon black pepper, more to taste
1 teaspoon chopped fresh rosemary
1 fat garlic clove, coarsely chopped
2 tablespoons extra-virgin olive oil
2 cups crème fraîche
1/4 cup white horseradish
Grated zest of half an orange
Season the tenderloin all over with the salt, pepper, rosemary and garlic. Cover the meat and refrigerate for at least two hours and preferably overnight. Let it come to room temperature for 1 hour before roasting.
Heat oven to 450 degrees. Wipe off as much garlic as possible. (It tends to burn.)
In a large, ovenproof skillet over high heat, heat the oil. Add the meat and thoroughly brown all over, 4 to 5 minutes per side. (If your skillet isn’t large enough, cut the meat in half.)
Place the skillet on the oven’s middle rack and roast until an instant-read thermometer shows 120 degrees (for rare), 10 to 20 minutes. Let the meat rest for 10 minutes before carving.
In a small bowl, whisk the crème fraîche, horseradish and orange zest. Season to taste with salt and pepper and serve alongside the tenderloin.