Summarising the steps here:
1) Season both sides of the steak generously with sea salt and pepper.
2) Place the steak on a grill over a baking dish.
3) Preheat the oven to 140 degrees, then put the steak in for 30 to 35 minutes.
4) Take the steak out and let it rest for 15 minutes.
5) Heat up the skillet until it is very hot, then fry the steak for one minute on each side.
6) Serve immediately.
The steak turned out perfect - evenly cooked inside, and well-seared outside with a balanced tinge of smokiness. That's it - I am going to use this method to cook all my steaks from now on.