Take the steak out of the fridge at least 2 hours before you plan to cook it and preheat an oven to 150.
Combine the mayonnaise, garlic, and dry ingredients in a bowl and then baste over all sides of the meat and add extra salt to form a crust. Leave to rest and marinate for a further 30 mins.
Let a cast-iron skillet come up to temperature on the stove at high heat, add a tablespoon of veg oil, and embrace the seal for 5 mins on each side. Add butter and fresh thyme and bask until glossy.
After 10 mins and a nice crust, you will need to cover the steak with foil and let it cook for a further 20 mins in the oven.
Turn the oven off and let it rest for a further 10 mins.
Notes
Before leaving to rest, make sure you spoon the remaining juices for a couple of minutes on top so it keeps moist for the ultimate tender steak.