Instructions:
- Pat the tenderloin completely dry with paper towels. If not tied, truss the beef every 1.5 inches with butcher’s twine to ensure even cooking. Allow the beef to sit at room temperature for 1 hour before cooking.
- Make the Herb Crust Paste: In a small bowl, combine the minced garlic, chopped rosemary, thyme, Dijon mustard, 1 tablespoon of Kosher salt, and 1 teaspoon of black pepper. Mix until it forms a coarse paste.
- Season and Marinate: Rub the entire surface of the tenderloin liberally with the herb paste. Wrap tightly in plastic wrap and refrigerate for at least 2 hours (or up to 24 hours) to let the flavours penetrate.
- Preheat and Sear: Preheat your oven to 400°F (200°C). Remove the beef from the fridge 30 minutes prior to searing. Heat the olive oil in your oven-safe skillet over medium-high heat until shimmering. Sear the roast aggressively on all sides (about 2 minutes per side) until a deep, dark crust forms.
- Basting Finish: Reduce heat to medium, add butter to the skillet. Once melted, tilt the pan and use a spoon to continuously baste the melted, foaming butter over the top of the roast for 1 minute.
- Roast: Carefully transfer the entire skillet (or the roast onto a rack set in a roasting pan) into the preheated oven.
- Monitor Temperature: Roast until the internal temperature, checked at the thickest part of the meat, reads 130°F–135°F (54°C–57°C) for a perfect medium-rare. This usually takes 30–40 minutes total.
- Crucial Rest: Immediately remove the roast from the oven. Transfer it to a cutting board, tent loosely with foil, and let it rest for a minimum of 15 minutes. The temperature will rise by 5–10 degrees during this rest.
- Slice and Serve: Remove any twine. Slice the Roast Beef Tenderloin thickly against the grain and serve immediately.