• Remove the beef tenderloin prior to cooking and allow to come to room temperature, about 2 hours depending on thickness.
• Pat the trimmed and twine-wrapped beef tenderloin dry with paper towels. Cut into two even pieces and season with kosher salt and pepper. Place on a wire rack on top of a sheet pan at room temperature for 2 hours.
• Combine the butter, garlic, thyme and rosemary in a small bowl. Set aside.
• When ready to cook, preheat the oven to 425°F.
• Heat oil in a large cast iron skillet or oven safe pan over medium-high heat. Once the oil is shimmering and the pan is very hot, add the beef tenderloin and sear each side for 3-4 minutes, about 12 minutes total, to create a golden brown crust.
• Slather the butter herb mixture over the top side of the beef tenderloin, then transfer the entire pan to the preheated oven. Roast for about 20 minutes for medium rare or until an instant read thermometer reads between 125-130°F as the meat temperature will continue to rise as it rests.
• Remove the beef tenderloin from the oven and transfer to a cutting board. Let it rest for 15 minutes. While the tenderloin is resting, prepare the gravy. Remove the twine and slice into 1-inch thick pieces.

For the beef gravy

• Transfer the beef drippings to a heat safe bowl and return about 4 tablespoons of the fat that rises to the top back to the pan, reserving the remaining drippings. Heat the same skillet over medium heat. Add shallot, carrot and celery and cook for 10 minutes, or until the vegetables are beginning to brown. Remove and discard the vegetables with a slotted spoon, taking care to reserve as much of the butter in the pan as possible.
• Add flour to the butter and whisk until a thick paste forms. Cook, stirring constantly with a wooden spoon for 1- 2 minutes, or until the roux starts to turn golden brown.
• Whisk in the beef stock, reserved beef drippings, soy sauce, and Worcestershire sauce and increase heat to medium high to bring to a boil. Reduce heat to a simmer, add thyme, and cook for 10 minutes, or until it has thickened slightly. Taste the gravy and see if it needs additional salt and pepper. Discard thyme and serve warm.