Cooking

Sure. First, cast iron pan is a must, since it has a high heat capacity because of its weight.

Your issue is the uneven distribution of heat, so use enough oil is important, at least as much to cover the bottom of the pan evenly.

Second thing is salt, if you salt it too early, it's going to absorb the water from the meat and create wet spots, which would be steamed instead of seared. Dryness is the key here, you either want to salt the steak immediately before adding it to the shimmering oil, or you can salt it and leave it uncovered in the fridge for a couple of hours for the it to dry off.

If the center is gray it's simply not touching the pan. Forget most of the lore and go with the science - you need the surface of the meat to reach 300F (150C) to create the Maillard reaction which is the "good" browning.

• Your pan should be hot (350-400F) to quickly boil off the surface moisture because any liquid water at the surface of the meat will prevent the temperature from rising above boiling point.
• Heavier pans will lose temperature less quickly (steel/iron, copper), and highly conductive pans (Aluminum, copper) will transfer the heat from your burner to your food more evenly.
• heat transfer on the stovetop is via conduction. Any part you want to cook at the temperature of the pan must be in contact with the pan. If you need to press down with a spatula or a weight on top to keep contact, go for it - but just enough to flatten, you don't want to drive moisture out. (see point one, above)
• Adding a thin coating of oil will increase the conduction between the pan and the meat. Micropores and surface irregularity will prevent complete contact with the pan; oil fills these micropores and allows more uniform heat transfer.
• When you flip the meat, make sure it lands on a previously unused portion of the pan. Where the meat is has been cooled by the meat itself, the area of the pan next to it is hotter.
• Don't move or slide the meat around. Set it in place and leave it. I can't remember the science on this (oops)
• Proteins on the surface are what form the Maillard reaction. Salting the meat will draw moisture to the surface and will also pull some proteins with it. The timing and drying and whatnot to get maximum protein on the surface is the subject of debate, but if you salt, give it a little time to work.

I dry, salt with Diamond kosher, sit for ~5 mins (prob too short, but I sous vide so I don't want the steak to cool too much), wipe on a very thin coat of EV Olive Oil then sear for about a minute a side on a 400F pan. I use both cast iron and non-stick aluminum on a 15,000BTU burner and find very little difference in the final result. YMMV