(Optional) The Day Before Cooking: Trim the beef tenderloin if needed, cut it in half, and tie it with butcher's twine. Season with salt and pepper, then refrigerate uncovered overnight or for at least 10 hours.

Day Of Cooking: If you didn't season the beef the day before, tie it up and season it with salt and pepper. Allow it to sit on the counter for about 2 hours to reach room temperature.

Preheat the Oven: Set your oven to 425°F (220°C) to ensure it’s hot enough to create a beautiful crust.

Sear the Tenderloin: Heat the avocado oil in a large cast-iron skillet over medium-high heat. Sear the beef tenderloin on all sides for 3 to 5 minutes per side until a golden-brown crust forms. This step is crucial for flavor!

Prepare the Herb Butter: In a small dish, mix the softened butter, garlic, horseradish, and herbs. Spread this butter mixture over the seared tenderloin, ensuring you get it into all the nooks and crannies. Insert a probe thermometer into the thickest part of the meat.

Roast the Tenderloin: Place the skillet in the preheated oven or transfer the beef to a baking dish and roast until it reaches your desired internal temperature, about 20 to 25 minutes. For medium-rare, cook until the thermometer reads 130-135°F (54-57°C); for medium, aim for 140-145°F (60-63°C).

Let it Rest: Once cooked, remove the tenderloin from the oven and transfer it to a cutting board. Let it rest for 15 to 20 minutes before slicing into 1" thick slices. This resting period allows the juices to redistribute, keeping the meat tender and flavorful.