Here's the method I use and it always works perfectly. An actual grill is better BUT this is 2nd best! (Timing is exact!)

Place "raw" cast iron skillet in oven and heat to 500 (260 C)

When oven reaches this temperature, remove pan and place it on stovetop over high heat.

Coat a room-temperature steak lightly with oil and salt/pepper.

Place steak in the middle of the hot, dry pan. Cook 30 seconds without moving. Turn (with tongs) and cook another 30 seconds. Then, put the pan into the hot oven for 2 minutes. Flip steak after 2 minutes and cook 2 additional minutes. (2 minutes is for medium-rare steaks. If you prefer medium, add a minute to both of the oven turns. If you prefer well-done, just put your steak directly into the trash.)

Remove steak from pan, cover loosely with foil, and let rest for 2 minutes.