Sprinkle a thin layer of salt on all surfaces of the steak. Place on a wire rack and refrigerate uncovered for about 20 hours.

Remove the steak and let it sit at room temperature for about 1 hour. Place the baking tray and rack in the lower part of the oven.

Bake at 250°F (120°C) for about 40-45 minutes until the internal temperature reaches 115°F-129°F (46°C-54°C).

Preheat a large cast iron skillet until it slightly smokes. Add a little extra virgin olive oil and sear the surface until golden brown.

Flip the steak, add butter, rosemary, and garlic. Baste the steak with butter until the internal temperature reaches at least 129°F (54°C), then remove from the pan.

Notes for next time:
The saltiness is just right, no more salt needed.
Try using the upper oven rack; the lower rack cooked a bit too long.
The cast iron skillet can be even hotter.
Try resting the steak after cooking; cutting immediately caused some juice loss.