If I use cast iron pan to sear it, and then put in the oven I have some questions:
If I sear it from both sides, one side 2 minutes, other 1 minute, and then put in oven for 6 minutes. Do I have to flip it half way? I wouldn't like one side to burn since the pan will be sizzling hot and will burn one side in the oven in those 6 minutes?
What is the usual temperature of the oven for this technique?
Shall I broil it, or have it somewhere in the middle?
Note that required oven time will depend significantly on steak thickness and oven temp.
It isn't necessary in all circumstances, but generally it will help to flip at least once. This is particularly important if transferring a heavy pan (like cast iron) into the oven.
Varies. Almost any oven temperature can work. The question is whether you want to cook your steak faster or want it to be more evenly cooked. The hotter the oven, the faster your steak will cook, but you'll have a thicker "gradient" from well-done to raw in the middle. In other words, the faster you cook, the thicker the gray "well-done" part will be near the surface in order to get the center up to temperature.
A very low oven might require you to cook the steak longer (perhaps even 30 minutes or more, depending on how low you go and how thick the steak is), but there's a better chance it will be close to "medium rare" (or whatever you like) all the way through. It will likely also be more tender and the fat will be softer.
Most people seem to like cooking steaks quickly, but there's no real benefit to a hotter oven other than getting the steak done faster.
Depends on what you're trying to do. Broilers cook by radiant heat, so they will likely cause more surface browning to occur. If your steak isn't dark enough after the sear and you want more browning on the surface, then broil. But broiling also tends to be a very high heat technique, so this is again more likely to produce a larger gradient in doneness. If broiling (particularly close to the broiler), flipping frequently is recommended.
Alton Brown did an episode on this actually, and the technique works perfectly:
Place a 10-to-12-inch cast-iron skillet in the oven and heat the oven to 500 F. Bring the steak to room temperature.
When the oven reaches temperature, remove the skillet and place on the range over high heat for 5 minutes. Coat the steak lightly with oil and sprinkle both sides with a generous pinch of salt. Grind on black pepper.
Immediately place the steak in the middle of the hot, dry skillet. Cook 30 seconds without moving. Turn with tongs and cook another 30 seconds, then put the pan straight into the oven for 2 minutes. Flip the steak and cook for another 2 minutes.
This time is for medium-rare steak. If you prefer medium, add a minute to both of the oven turns.
Remove the steak from the skillet, cover loosely with foil and rest for 2-5 minutes.
I would take note of the thickness of your steak and insert a probe thermometer in it while it's cooking so you know how long it takes to reach the doneness that you like.
I personally just put the pan in the oven and when it reaches 500F I take it out and put it on the burner over high heat. Cook for 30-60 seconds per side, and then put it in the oven for 4 minutes, flipping halfway through. Put the steak on a cutting board with a pat of butter and some finishing salt, and rest for 5-10 minutes.
Oh, and please remember to put an oven mitt on or something to warn you that the pan is going to be extremely hot. I've made this mistake more than once, and it's not fun.
I've found a reverse sear gives me a greater margin for error - much harder to screw up. It works like this:
This technique is based on some things I learned from Kenji: http://www.seriouseats.com/2012/12/the-food-lab-complete-guide-to-pan-seared-steaks.html
