Season the Steak: Generously season ribeye with kosher salt and pepper. Optional: dry brine in fridge 1–3 days.
Prepare for Cooking: Pat dry. Place steak on a wire rack. Preheat oven to 250°F (121°C).
Reverse Sear Step: Cook steak until internal temperature is 10–15°F below your target doneness.
Rest the Steak: Let it rest 5–10 minutes.
Sear in Cast Iron: Heat skillet until smoking. Add a little oil, then sear steak 1–2 minutes per side.
Optional Butter Baste: Add butter, herbs, and garlic during final minute and spoon over steak.
Serve: Rest briefly, slice, and top with garlic-herb butter.