Bring the steak 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 fat side down in the centre of the pan. Cook on this side until more of the back fat has melted and is a good brown colour.
Lay it on its side and cook for 2-3 minutes. After this, turn over onto other side for another 2-3 minutes.
At this point the steak should be wonderfully seared. Reduce the heat down a bit and keep on turning the steak every 2 minutes for around 15 minutes.
It will take around 10 mins, you are aiming for 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 temp.
Slice and serve with a good red wine for a wonderful feast.