Cooking "steak tips" on the grill - how to avoid making them tough? Recently we bought some "steak tips" from a local farm, and cooked them on our grill and were very unhappy about the result - they were very tough, although the flavor was ok. I wanted to see if someone could see my mistake (I have lots of broiling / pan frying steak experience, but very little on the grill).


These steak tips (which I'm assuming were "beef flap") were like 6" long, 3" wide and 1/2 - 1 " thick. First time, no marinade. They came frozen, so we thawed them in cool water.
Preheat the gas grill to over 500 F.
Throw the steaks on
Cook 2 minutes a side, flipping frequently (as per Cook's Illustrated's advice).
Cooked to ~130 F in the middle, which was cool pink to hot pink, roughly what we like. (different sized steaks were done slightly differently of course).
Tent for 5 minutes in foil.


And they were very tough. Second time I tried an overnight marinade, and also attempted to slice the steaks across the grain (which is how we prepare skirt steak), and they were still very tough.

I've seen lots of advice, which is mostly where I came up with this basic procedure. Where did we go wrong?

(I'm hoping for some advice specifically about steak tips, but if my method is flawed I would like to know that as well!)
Tough meat boils down to 3 factors: 

The way it's cooked, the way it's cut and the quality of the meat.

I know this is an old question, but next time you encounter tough meat on the grill, perhaps try pan frying it. If its still tough as rocks, I would question the quality of perhaps that batch of meat, provided it was cut properly.