Remove steak from refrigerator and let sit at room temperature for at least 10 minutes. Pat dry with paper towels.

Heat cast iron or carbon steel pan over medium heat until very hot.

Season steak generously with kosher salt and freshly ground black pepper on both sides (use about 30% more salt than usual).

Add 1 tablespoon oil to pan and swirl to coat. Gently lay steak away from you in the pan. Cook ~5 minutes until deeply browned and crusted. If there is a fat cap, stand steak on its edge to render fat before flipping.

Flip steak and cook another ~5 minutes until medium-rare (internal temp 120°F).

Transfer steak to cutting board and rest for same amount of time it cooked (~10 minutes).

Let skillet cool for 2 minutes, pour off excess oil leaving browned bits.

Return pan to medium-low heat; add shallot, garlic, thyme, and 2 tablespoon cold butter. Swirl and whisk until butter melts and shallot softens and browns (~3-4 minutes).

Add ½ cup water and whisk to loosen browned bits. Stir in Dijon mustard and Worcestershire sauce until smooth.

Add remaining 2 tablespoon butter; whisk until sauce is emulsified and slightly thickened (~1 minute). Remove from heat. Taste and adjust seasoning.

Slice steak against the grain into ½-inch thick slices; arrange on plate.

Spoon pan sauce over steak and serve immediately.