Bison (Buffalo) Flank Steak

Linda and I love flank steak. My dad turned us on to it several years back and we've been eating it regularly ever since. This past Saturday we were shopping at Whole Foods and they had Buffalo Flank Steak on sale for less than $10.00/lb. So I bought  a small one that weighed in at about 12oz. I didn't freeze it; just left it in the 'fridge until this morning when I pulled it out, unwrapped it, drizzled it in EVOO and balsamic vinegar, seasoned it with salt and pepper, covered the glass container sheltering it and put it back in the 'fridge to marinate throughout the rest of the day. I guess about 5 hours or so. This evening I grilled it over high heat for about 15 minutes and served it with steamed zucchini, fresh tomatoes and mozzarella. It was delicious. In fact, I believe it was the best tasting flank steak I've ever eaten. I would be hard pressed to say it tasted any different than beef but it sure was much more tender. Very surprising. I laugh because when I bought it the butcher said "you do know this is bison, don't you" like there was something wrong with it.