Pre heat oven to 350 degrees

Heat cast iron pan to medium heat and butter it (3-4 minutes?)

Season the steak(s) with a little sea salt and pepper

Place the seasoned side down on the pan for 2 minutes to sear in flavor. Once the 2 minutes is up, they not stick at all and have a nice browning. (continue to next step during this time frame)

Season the current side up with the same seasonings while the first side is searing. (again continue)

Flip them over to sear on the other side for another 2 minutes.

Once completed, move them (on the pan as they are) into the oven for 9 minutes. Flip about 4 minutes through

Check the temperature of the thickest one. You want it to be about 120-125 degrees. If lower, put them back in for a couple more minutes.

Once at the goal temperature, take them off the pan (a plate is a good place for them) and cover in tin foil. After about 5 minutes, check it once more and the temp should be about 130-135. This should be perfect medium rare and ready to serve! Finish up with any additional seasonings you wish to add.