If you have 30 minutes to spare (or more), season the steaks on both sides with salt and set them aside. The salt will pull some juices out of the meat, dissolving the salt, and after some time sitting will reabsorb back into the meat, bringing the salt with them to give you seasoning throughout.
Heat a cast iron pan over medium heat for a good while—say, 5-10 minutes—to get it hot (or put it in a 350-400° oven for 20 – 30 minutes, which will give you more consistent heat, without cold spots).
Smear the steaks with a t-spoon of oil each, and slap them into the hot pan. Sear for just 2 minutes before flipping them over, and cooking an additional 2 (this gets you somewhere in the ballpark of medium-rare, so adjust the time to suit your preference—though be cautious, as some cuts are not suited for being cooked much past a soft medium).
Anyway, remove the pan from the heat and the steaks to warm plate. Cover the meat with foil and set aside.
If the pan seems very dry then add the last t-spoon of oil before adding the anchovies. If the pan is smoking hot then give it a few minutes to cool; what you want is for the anchovies to almost melt into the oil, and if it’s too hot they will just fry and frazzle. Stir them into the pan, breaking them up to help them melt.
Add the chili flakes and oregano, and stir for just a few moments before tumbling the tomatoes, olives, and pepperoncini. Toss them in the hot pan until you see the tomatoes begin to take notice of the heat, softening slightly—just a minute or two.
Pour in the vermouth, scrape the bottom of the pan with a wooden spoon, and simmer 3 – 5 minutes, until the sauce is reduced and thickened slightly, and the tomatoes burst a bit.
Move the steaks to warm serving plates, pouring any juices that collected on the plate while resting into the simmering pan, and spoon the sauce over top, scattering with parsley for a final flourish.
-If you wanted to make this for a larger group of people you could do this sort of tagliata style; a London broil/flank steak/top round steak/top blade steak can get seared in a hot pan to medium-rare (or medium), thinly sliced, and topped with the sauce before serving.