Bring the tomahawk steak to room temperature for 30 to 60 minutes
Pat the steak dry with paper towels
Season generously with salt and black pepper on all sides
Preheat the oven to 400°F
Preheat a cast-iron skillet or heavy pan over high heat
Add a small amount of high-smoke-point oil to the pan
Sear the steak for 2 to 3 minutes per side
Sear the fat cap and edges briefly
Transfer the skillet to the oven
Cook until the internal temperature reaches your desired doneness
Remove the steak at 120°F for rare
Remove the steak at 125°F for medium-rare
Remove the steak at 135°F for medium
Rest the steak for 10 to 15 minutes
Slice against the grain
Serve immediately