Thanks for all your suggestions.
Yes, I did let it stand and I did cut across the grain.
I used Masterpiece Steakhouse marinade, which smells good and strong.
I'm not a fan of Rachel Ray's either, but I see she cooked her flank steak on an indoor electric grill or stove top grill pan. I do have an electric grill and tried it and it did come out better, but still not like I had in the restaurant. I wouldn't even try it on the stovetop, as in the past have not had luck with steaks that way.
The one I had in the restaurant had a totally different texture and was very, very tender. I ordered it med/well. It came in the whole piece and not sliced, so I was cutting it myself.
I think the ones I made were as you said "Muscley" and "Gamey" (Oops! hope I don't sound like Rachel Ray making up expressions and words). but that's a good analogy, since you said it comes from the muscle section- and I did cut across the grain in very thin slices.
I didn't realize that these were tough cuts of meat, as they are expensive on Long Island, NY. You can get porterhouse or ribeye for the same price or even cheaper when they have a sale. I've rarely seen flank or skirt on sale and they seem to be hard to get, as most times the store doesn't have them.
I have 2 more in the freezer. I'll try this again. If not, I have 2 dogs, who will enjoy them.