Preheat your oven to 450°F (232°C). Let the beef tenderloin sit at room temperature for 30–45 minutes before cooking.
In a small bowl, mix together olive oil, garlic, rosemary, thyme, salt, and black pepper. If using Dijon mustard, spread it over the roast first, then rub the herb mixture all over the beef tenderloin.
Heat a large cast iron skillet or oven-safe pan over medium-high heat. Sear the tenderloin on all sides until browned, about 2–3 minutes per side.
Transfer the pan to the preheated oven and roast for 20–25 minutes, or until the internal temperature reaches 125°F for rare, 130°F for medium-rare, or 135°F for medium.
Remove from the oven, tent with foil, and let rest for at least 15 minutes before slicing.
Slice into thick medallions and serve with your favorite sides or a drizzle of horseradish cream, red wine sauce, or garlic herb butter.