Remove the filets from the refrigerator 30–45 minutes before cooking (longer for thicker steaks) so they come toward room temperature. Pat thoroughly dry on all sides with paper towels.

Season

Generously season both sides and the edges of each filet with kosher salt and freshly ground black pepper. Press seasoning lightly into the meat so it adheres.

Preheat pan and oven

Preheat a heavy ovenproof skillet (cast iron preferred) over medium-high heat for 5 minutes until very hot. Preheat oven to 400°F (200°C).

Sear

Add the neutral oil to the hot skillet and swirl to coat. Carefully place filets in the pan with space between them. Sear without moving until a deep brown crust forms, about 2.5–3 minutes per side for a 1½–2 inch steak. Sear the edges (fat side) for 30–45 seconds using tongs to roll the steak onto its side.

Add aromatics and butter

Reduce heat to medium. Add the unsalted butter, crushed garlic cloves, thyme, and rosemary to the pan. As the butter melts and foams, tilt the pan slightly and use a large spoon to baste the steaks continuously with the foaming butter and aromatics for 30–45 seconds to build flavor and color.

Finish in oven

Transfer the skillet to the preheated oven to finish cooking to desired doneness: about 4–6 minutes for rare (120–125°F), 6–8 minutes for medium-rare (125–130°F), 8–10 minutes for medium (130–140°F). Use an instant-read thermometer inserted into the center to check temperature.

Rest

Remove filets to a warm plate or cutting board and loosely tent with foil. Rest 6–8 minutes (longer for thicker steaks). During this time carryover cooking will raise the internal temperature slightly and juices will redistribute.

Serve

Optionally slice or serve whole. Spoon any pan juices or reserved butter and herbs over the steaks. Serve immediately.

Optional pan sauce

Sauté shallot

After removing the steaks from the skillet, place the pan back over medium heat. If there is excessive fat, pour off all but about 1 tablespoon. Add the minced shallot and sauté 1–2 minutes until softened and fragrant, stirring to release browned bits from the pan.

Deglaze

Pour in the red wine or beef stock to deglaze, scraping the bottom of the pan with a wooden spoon to lift fond. Bring to a simmer and reduce by about half, 3–5 minutes, until slightly syrupy.

Finish sauce

Whisk in the Dijon mustard, then remove the pan from heat. Whisk in the cold butter pieces one at a time to emulsify and thicken the sauce. Taste and adjust with salt and pepper as needed.

Serve with steak

Spoon the warm pan sauce over the rested filets or serve on the side.