This works great for flat iron steak, or any long thin (and tough) piece of meat (seen here is a "round" steak).
Puncture meat all over with a fork. Cover with sea salt, pepper, and whatever herbs sound good to you (here I have used basil just dried from the garden), as well as extra virgin olive oil and balsamic vinegar. I also added some raw apple cider vinegar.
Let sit at least 15 minutes, and up to an hour (but cover with something to keep bugs and dust away).
Broil for 5 minutes and let stand for 5 minutes (based on 1" thickness), or grill for 2.5 minutes per side and then let stand 5 minutes .
You can slice this into steak servings, cut it thin for fajitas, and make sure to save any leftovers for steak Caesar salad later.