Bring to room temperature and dry all over with kitchen towel. Season lightly with sea salt and pepper.
Take a hot castiron pan and without adding any oil place the steak in the centre of the pan. Make sure that you place the steak into the pan the thin fat side down. Cook on this side for 5 minutes.
Turn over and cook on the other side for 2 minutes. After 2 minutes, turn over onto the final unseared side for another 2 minutes.
At this point the steak should be wonderfully seared all the way around. Reduce the heat down a bit and keep on turning the steak every 2 minutes.
It will take around 15 mins to get to a core temperature of 40°c. After this the steak should feel slightly springy when pressed.
Remove and cover loosely with foil to rest for around 15 minutes at room tempurature.
Slice and serve with a good red wine for a wonderful feast.