when i cook a steak using this pan method i always go with a thick cut. Striploin perhaps....this allows you to sear it longer in the pan without overcooking it. And when I do I use oil and butter combination. The theory is the oil burns at a higher temperature than butter does. If you use them both, the oil dilutes the butter keeping it from burning. Butter also gives it a nice sear. Add your steak when the butter foams and depending on thickness, maybe 6-8 minutes per side with your heat a little higher than medium. Cant stress enough the importance of good cookware. If you decide to sear for only a couple minutes either side, and finish in the oven...do NOT use a lid. This will steam the steak and you will lose the sear...
threadstarter, make that steak perfect tonight. And dont forget to let your steak rest when its done cooking...and when you're done cooking, whip up an herb butter, and let a dollop melt overtop while it rests