Optional: Pat steak dry with paper towel. Rub evenly with salt and worcestershire sauce, if using. Place steak on wire rack set in rimmed baking sheet; place in the refrigerator, uncovered for 24 hours.
If you skipped step 1, pat steak dry with paper towel; rub steak evenly with salt only. Set steak aside at room temperature for 30 minutes. Pat steak dry again before continuing.
Meanwhile, in a small bowl, mix together all ingredients for spice rub, breaking apart any chunks of brown sugar. Rub steak evenly with spice rub.
Heat oil in 12-inch cast iron skillet over medium heat until oil is shimmering, about 3 minutes. Set steak in skillet; cook without moving for 3 minutes. Flip steak over; cook for 2 minutes. Continue cooking, flipping every 2 minutes, until steak is well browned on all sides, and temperature at thickest point registers 125 °F for medium rare, about 10 minutes total; or 135 °F for medium.
Transfer steak to cutting board, and tent loosely with aluminum foil. Rest steak for 10 minutes. Slice steak 1-inch thick, and serve.