This is my personal fail safe method for a rear steak. It's been tested over many years. It gives a good dark crust with soft meat of what ever shade of red/pink/brown you prefer within.
Take the steaks out of the fridge a good couple of hours before you cook them. Dry them by resting them on clean kitchen roll and rotating and changing it as necessary. You want them as dry as possible sothey crust rather than steam when they hit the hot pan.
Preheat a cast iron pan for at least 40 minutes. It should be so hot you can only hold your hand 5 inches above it for a few seconds.
Lightly oil and salt/pepper your room temp, dried steaks and sear for 30 seconds on either side. Leave on fresh, clean kitchen roll for 10/15 minutes. Change the paper if necessary. More excess water will drain out. Put back in the hot pan for another 1 min either side. Leave to rest on yet more fresh dry kitchen roll for 15 minutes.
That will probably be enough for anyone who likes a rare steak. If someone likes it medium , do another 45 second round. If they like it welldone then a 4th go will do it. You could do a 5th go but you probably won't need to.
If I'm cooking for a few people I start with those who like it well done, then I do the mediums in the second round and I only add the rare/blue/properly cooked steaks for the last two rounds.
Be warned - this method generates a lot of smoke. Even flames if the steak is fatty. Have the extractor fans on, the windows open and a small child or willing adult prepared to flap a tea towel at the smoke detectors if necessary.
Drying it before and during cooking ensures a good, flavoursome crust rather than the slightly flabby finish that cooking (essentially steaming and then drying) a damp steak can give.