Whole Flat Iron Steak

Meat Cuts 101: Flat Iron


NAMP Number: 114D
Muscle Name:  Infraspinatus
Other names:  Butler’s Steak, Oyster Blade Steak, Top Blade, Patio Steaks, Paleta, Espaldilla de Planchuela, Puffer Steak
Cooking style: Quick – a trimmed down flat iron is barely a 1/2 inch thick.  Sear it good both sides and call it a day.

It seems like spring is finally arriving to my sleepy corner of PA.  The birds are chirping, flowers are blooming, and most crucially – my beloved Weber has finally reappeared from the snowbank it spent the last 5 months hiding inside.  It’s reemergence has put grilling firmly in my mind and at this point I’ve been thinking about firing up the grill so much I can practically smell the charcoal.  What’s great about the grill is that it’s a great way to cook just about any cut of meat you can think of.  There are certain cuts, though, that just cry out to be grilled; they are so well suited for the insanely hot, dry sear you get from charcoal that it’s almost a shame not to grill them.    For me, almost no steak grills up better than the Flat Iron.

Somehow still constantly referred to as a “new” cut, the Flat Iron has been around for years under a slew of different names.  Most commonly referred to as a Top Blade, or Oyster Blade steak, the flat iron has recently enjoyed a resurgence among “obscure meat cuts” think pieces, and on dorky meat blogs (heyooo).  Flat irons are pretty recognizable as a whole muscle.  They’re characterized by spiderweb-like marbling, and a long rectangular shape which fans out at one end.  When left whole, the muscle has a large vein of sinew running through the middle.

In the past the steak was cut against the grain, leaving the strip of insanely tough sinew bisecting the steak like a rubber band.  You could cook that thing all day and it wouldn’t get any less tough.  Because butchers today are smarter than that (and better looking too), common practice is to cut the flat iron into two thin pieces while removing the sinew entirely.  This leaves it with a thickness similar to skirt steak or bavette, but with a much tighter grain structure.

Close up of the amazing marbling on the Flat Iron.
The tighter grain, and thus thinner sarcomeres, is the reason behind one of the more interesting facts about the Flat Iron – it’s actually the second most tender muscle on the entire animal.  Meat dorks with PhDs and big foreheads have something called a Warner-Bratzler Shear Machine, which looks a lot like a miniature meat guillotine. They use this device to subject a core sample of a particular steak to a precise set of measurements which they ultimately use to determine tenderness.  These tests are so precise that they even specify which device you’re allowed to cook the meat on (this dorky thing if you’re interested in underwhelming your friends the next time you have a party).  Coming in first, to no one’s surprise was good old psoas major – beef tenderloin.  But what really blew people’s minds was when our friend the Flat Iron came through with the second best shear force score (3.2kg if you care.  Which, why would you?).

Since a little marinade never hurt anything that’s going to end up on the grill, I’m passing along one of my favorite dead simple marinade recipes.  Don’t feel compelled though, a good Flat Iron steak from a well-raised animal is packed full of flavorful marbling and even just some salt and pepper will be enough to really make this cut sing.

Balsamic Marinated Flat Iron Steaks

1/4C Balsamic Vinegar
1/4C Olive oil
2tsp kosher salt
2 cloves garlic, minced
1Tbl spicy brown mustard
1 sprig fresh thyme
Juice and zest from half a lemon

2-4 good sized flat iron steaks, sinew removed.

1.  Combine all the ingredients in a bowl.  Probably have some bread handy to dip in there – trust me on that one.

2.  Marinate your Flat Iron steaks (or whatever really) for at least an hour, but no longer than overnight.

3.  Take out of marinade, pat dry, and leave out for an hour or so to come up to room temp.

4.  Sear in a hot pan, or ideally on a grill over hot coals.  2-3 minutes a side should be sufficient for a good mid-rare.  Don’t forget to let them rest.

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