<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What the heck, its a steak! You can hardly go wrong (unless it was the "grass fed" rib eyes I cooked last night - TOUGH!) </div></BLOCKQUOTE>
Grass-fed beef can be either grass-finished or grain-finished. If grass-finished (rather than the typical feedlot-finished beef, where grain is fed) the steaks need to be cooked a bit differently. High heat is only worthwhile for a very brief period. I don't bother with very high heat at all, preferring to build the sear. Very high heat can toughen grass-finished beef; it can be the ruin of bison, which is nearly always grass-fed and -finished.
Flat irons are one of my favorites. They are cut from the chuck top blade, which is another name for them. There are, however, two ways to cut chuck top blade: if the roast is merely crosscut into steaks, as one would cut, say, a whole sirloin or tenderloin, the resulting steaks (usually called chuck top blade steaks) have a line of gristle is the center which does not break down well if grilled as steaks. If cut for flat iron steaks the roast is instead cut horizontally above and below the gristle line so the gristle is eliminated.