Frying Steak - disappointing gray crust, not pink inside
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