If you have time, prep the steaks the night before by applying a generous amount of kosher salt and placing uncovered on a rack in the refrigerator.
Heat your grill to 225 - 250°F. Use a water pan to help maintain a nice low temperature.
Place the steak on the cool side of the grill and close the lid. Cook until the internal temperature reaches 80°F.
Flip the steak to ensure it heats through evenly. At this point you can start your charcoal chimney for the final sear.
For medium rare remove steak from the grill when it hits an internal temperature of 110 - 115°F. Set steaks aside while you prep the grill for searing.
Empty a full chimney of hot lump charcoal on top of the briquettes and then return the grill rack.
Sear the steak over the intense heat flipping regularly and making sure to get a good crust on each side. Two - three minutes total depending on the size of your steak.
Remove steak from the grill when it hits 130-135°F for medium rare. Leave to rest for a few minutes before slicing and serving.
While steak is resting is the perfect time to finish any sides. I recommend grilled broccolini.