forget time. forget temp.

sear it til it looks beautiful. someone who loves char will tell you 3 minutes a side. someone who likes pretty lines on a steak will say 90 seconds. so sear til it looks to you like a picture perfect steak.

after that, you are finishing to 'doneness'.

pull it off and shut the egg down to 400 or so. then throw steak back on to roast until 'done'. open it maybe 3 minutes in to the second part of the cook and prod it, or take its temp.

you will need to figure out how you like your steak, and you'll need to learn how to tell when it's there.

there's the thermapen (best and simplest, clearest way).

but you can also try this. make a loose fist. with your other index finger, push on the fat part of your thumb (below your fingertips, the big 'ball' of your thumb). that feels like what 'rare' feels like.

tighten that fist now as hard as if you were gonna punch celtic wolf. touch the heel of your thumb again. that is how "well done" feels when you press it with a finger.

loosen it a bit, but not as loose as the start. that's medium.

kind of tough to convey, but that's the idea. get a thermapen and you'll never overcook again. ...just remember to take the steak off about 7 degrees under the desired temp, as it will continue to cook on the plate too.