Season both sides of each filet generously with kosher salt (about 1/2 tsp per side per steak) and freshly ground black pepper. Press seasoning into the meat so it adheres.

Preheat pan

Place a heavy-bottomed skillet or cast-iron pan over medium-high heat and let it get very hot (about 3–5 minutes). Heat is crucial for a good sear.

Sear steaks

Add 1 teaspoon neutral oil to the pan and swirl. Place filets in the pan without crowding (work in two batches if needed). Sear undisturbed for 2.5–3 minutes to form a deep brown crust.

Flip and baste

Flip the filets and immediately add 1 tablespoon butter, 2 thyme sprigs, and two crushed garlic cloves to the pan. Tilt the pan slightly and use a spoon to baste the steaks continuously with the melted butter for 2–3 minutes until an instant-read thermometer reads 125°F (52°C) for medium-rare. Adjust time for desired doneness: about 120°F for rare, 130°F for medium.

Rest

Transfer filets to a warm plate or cutting board and tent loosely with foil. Rest 6–8 minutes so juices redistribute while you make the pan sauce.

Finish

After sauce is ready, spoon the warm sauce over each filet and garnish with the remaining fresh thyme and a small pat of butter if desired.

Pan Sauce (red wine and shallot reduction)

Prepare pan after searing

After removing steaks from the pan (leave brown fond and any rendered butter and aromatics), reduce heat to medium. Carefully pour off any excess fat, leaving about 1 tablespoon and the browned bits in the pan.

Sweat shallot

Add 1 teaspoon extra-virgin olive oil if pan is dry. Add the minced shallot and cook, stirring, for 60–90 seconds until soft and translucent but not browned.

Deglaze with wine

Pour in 1 cup dry red wine to deglaze the pan, scraping up browned bits with a wooden spoon. Bring to a simmer and reduce by about two-thirds, approximately 4–6 minutes, until slightly syrupy.

Add stock and mustard

Stir in 3 tablespoons beef stock and 1 teaspoon Dijon mustard. Continue simmering gently until sauce coats the back of a spoon, about 2–3 minutes more.

Mount with butter and finish

Remove the pan from heat. Whisk in the 2 tablespoons of cold cubed butter, one cube at a time, to emulsify and thicken the sauce. Stir in chopped parsley and season to taste with 1 teaspoon salt and 1/2 teaspoon black pepper.

Strain (optional)

If a silky sauce is desired, strain the sauce through a fine-mesh sieve into a small saucepan or bowl, pressing on solids to extract flavor, then return to gentle heat to keep warm.