Step 1: Prepare the Beef Tenderloin

1. Preheat your oven to 425°F (220°C) and allow the tenderloin to come to room temperature for about 30 minutes. This ensures even cooking.
2. Trim any excess fat or silver skin from the tenderloin if it hasn’t already been done. Use kitchen twine to tie the tenderloin at 2-inch intervals to create a uniform shape, ensuring even cooking.

Step 2: Season the Tenderloin

1. In a small bowl, mix the minced garlic, salt, pepper, rosemary, thyme, and 2 tablespoons of olive oil. If using Dijon mustard, mix it into the herb rub for an extra layer of flavor.
2. Rub the mixture evenly over the entire surface of the beef tenderloin, pressing it gently to adhere.

Step 3: Sear the Tenderloin

1. Heat the remaining tablespoon of olive oil in a large oven-safe skillet or roasting pan over medium-high heat.
2. Sear the tenderloin on all sides until it develops a golden-brown crust, about 2 minutes per side. This step locks in flavor and enhances the texture.

Step 4: Roast the Tenderloin

1. Transfer the skillet or pan to the preheated oven. Roast the tenderloin until it reaches your desired internal temperature:
   • Rare: 120-125°F
   • Medium-Rare: 130-135°F
   • Medium: 140-145°F
     Use an instant-read thermometer inserted into the thickest part of the meat for accuracy.
2. Depending on the size of the tenderloin, roasting typically takes 25-35 minutes for medium-rare.

Step 5: Rest the Meat

1. Remove the tenderloin from the oven and transfer it to a cutting board. Tent loosely with foil and let it rest for at least 15 minutes. Resting allows the juices to redistribute, ensuring tender and juicy slices.

Step 6: Make the Pan Sauce (Optional)

1. While the tenderloin rests, prepare the pan sauce. Place the skillet with drippings over medium heat. Add the red wine, scraping up any browned bits from the bottom of the pan.
2. Stir in the beef stock and simmer until the liquid reduces by half, about 5 minutes. For a thicker sauce, whisk in a teaspoon of flour or cornstarch.
3. Finish by whisking in the butter until melted and glossy. Serve the sauce alongside the tenderloin.