Frying Steak - disappointing gray crust, not pink inside

Too much oil, probably...Oil will prevent proper caramelization. Also, sounds like the oil you used had a low smoke point, though really you have to expect to fill the house with smoke any time you sear/blacken on the stove.

With a thin steak, it's going to be very easy to overcook. I wouldn't bother letting them sit out: that's more to get a nice uniform pink on a thicker cut of meat, or to prevent a large roast from being undercooked in the center and overcooked on the outside. A few minutes on both sides, and you'll probably be fine.

It sounds to me like you've made a good start and almost got there. You picked a heavy pan and got it hot, and you had in mind the outcome you want. You also recognized that you needed to get your steaks off the pan before they overcooked, showing you have the theory and practice down. Here's the tweaks I would make to get the result you want:

• Oil: Olive oil is a great cooking oil for low temperature but it is not a good choice for high temperature as it will 1) smoke, 2) set on fire in some cases (it's flare-up city on the barbecue) and 3) produce off flavors (as in taste bad). Canola (rapeseed), peanut, sunflower, safflower, ie most vegetable oils will work fine for this. You only need a small amount ensure good heat contact with the pan, not a liberal coating
• Seasoning: salt is fine to put on your steak, pepper will burn and turn bitter, I suggest you pepper it just after cooking
• Steak choice: Even on a hot pan there won't be enough time to get enough crust on a flank steak (or any thin steak) before the meat inside is done, if you want a crust then you're better off with a thicker steak. A grey outside without any crust is typical with a thin steak. When buying a steak remember that you're better off getting quality over quantity, a small piece of good quality filet or ribeye is better than a slab of a tough old rubber. Personally I have no problem with flank steak, I suggest you marinade it first and get your barbecue working again as a searing hot flame is the way to go for flank

The bland grey is typically caused by the meat steaming. You want to dry off your steaks just before cooking them. This will allow the surface to get hotter, as there's no moisture evaporating.

As for the oil -- if you want to cook in a bit of oil, so that you can ensure better heat transfer, until you're experienced with how hot you need to have the pan, you should put a thin layer in the pan. As the oil heats, it will 'shimmer' ... basically, it'll start having small ripples/waves in it. This will happen just before it starts to smoke. You might even let it get to where there are just a couple of whips of light smoke coming off the pan.

This is your sign to add the steaks. (immediately if you waited for it to smoke). The meat will cool down the pan slightly, so it won't go to full on smoking. Mind you, the oil will reduce some of the browning, as Satanicpuppy mentioned, and it's preferable not to let it sit out for thin steaks. (Unless you're going for well done, and then you do not want a hot pan; you need to cook over more gentle heat for that).

Something that has been mentioned yet... I like steak medium rare and I have no trouble frying a thin steak to medium rare but there's a couple of things to bear in mind.

The area that a steak covers in a pan is important - area not volume. It doesn't matter how thick your steak is since the hot pan with some oil is what sears the surface preventing the meat juices running out. When the juices run out freely, you're essentially boiling your steak. If you put too many steaks in the pn at one time (too much surface of the pan covered), it lowers the temperature too much as the meat surface won't be seared.

This can be seen if you try to brown sliced mushrooms. If you put a small amount in a hot pan with oil and stir a couple of times, you get golden brown surfaces with still some body to them. Put too many in and the water comes out making them soggy and grey. (I initially learned this years ago before the internet).

Another thing is lean meat contains more water than well marbled meat which makes sense if you think that the fat on meat as little water in it. The water content of flank steak is roughly 70%. Mushrooms are 92%. If mushrooms can be browned without overcooking them so can thin steak.

My technique is to have cold steak - directly from the fridge - and put it in a very hot cast iron frying pan when the oil just starts smoking. Cast iron is heavy and won't cool off quickly like a thin lightweight pan will. I never overcrowd the pan. At least 2/3 of pan's surface is still bare. I keep the pan on a fairly high heat and ready to turn it up all the way if needed. Each side only gets between 1 to 1 1/2 minutes per side (one of us prefer to have red juices run out when the steak is cut). Through practice, I've become good at judging how thin the steak can be for time. I never go thinner than 3/4 inch (2 cm) as they'll be too cooked.

Whatever food you plan on browning but not fully cooking, it's important for the pan to stay very hot and too much food in it at one time cools it too much. This may not be standard advice as it seems most people believe it's not possible to cook thin steaks to medium rare. This always works for me but I'm only cooking for two. I don't mind doing this in two batches if necessary.

If you're looking for crust on a steak you may want to just flour it a little or use egg and cracker or something like that before you fry it. Cast iron is great idea...good luck in future cooking....oh fried steak is good but grilled is the bomb.

First of all, flank steaks are not a good steak to get a good crust on. You would want to use something thicker like a sirloin and a rib eye cap. Second of all, never ever cover your steak with tin foil, that will cause the steak to overcook cause of the steam and you’ll lose your crust because it will get steamed off. Third of all, try using a cast iron pan or a stainless steel pan, let it heat up for at least 6 minutes on medium-high heat and for the oil, use a neutral oil like, canola or peanut oil.