Beef Loin Flap Steak at Costco: Great Meat for Fajitas and Stir Fry!

The Beef Loin Flap Steak at Costco is tender, delicious and perfect for fajitas and stir fries.  There are are few things to consider before you buy this steak and, if you want to make fajitas, there is a better option in the meat counter.

Costco Beef Loin Flap Steak

What is a Beef Loin Flap Steak?

The Flap steak comes from the bottom sirloin section of a steer and is easily confused with skirt steak.  Like all steak cuts from the sirloin, the Flap has plenty of beefy flavor.

The Flap, also known as a Bavette Steak, has long strands of loosely connected muscle fibers that, when sliced against the grain, are incredible tender.  The open grain structure also means that this is one of the few steaks that will soak up a significant amount of flavor from marinades.

The combination of great flavor and tenderness is what makes this steak great for fajitas and stir fries.

Flap steak currently (June, 2021) costs $12.99 per pound which makes it almost as expensive as a Ribeye.

Costco Flap Meat Must be Cooked to 145F.

One of the downsides of this steak is that it must be cooked to at least Medium (145F) which many people, including me, consider to be overcooked.

This steak has to be cooked to 145F because Costco uses Blade Tenderization to increase tenderness.  Most stores wet age their beef to increase tenderness but that process takes time.  Costco is all about rapid inventory turnover so they take a shortcut and blade tenderize their steaks.

Blade tenderization basically involves using punching the steak with a press full of needles to break up the muscle fibers.  Because the meat has been punctured multiple times it must be cooked to 145F in case any bacteria was introduced.

The warning about blade tenderization is on the label of most Costco steaks but most people don’t notice as they are only looking at the price tag.

There is a Better Choice for Fajitas

You can soak flap meat in a marinade and make great fajitas but as long as you are shopping at Costco you might want to look at another option.

Costco usually has a marinated skirt steak for sale that is less expensive than the Flap and is absolutely delicious. This is my “go-to” cut for fajitas now since they are already seasoned and I can throw it on the grill as soon as I get home.

Because this skirt steak has been both marinated and tenderized you need to cook it to at least 160F but there is so much marinade injected into this thing that it still stays tender and juicy.

Marinated Skirt Steak at Costco

Of course, if you want complete control over your fajita marinade then go ahead and buy the Flap steak.

Another cut of meat at Costco that is great for fajitas and much less expensive than Flap, is flank steak.  You can check out Flap Steak vs Flank Steak to learn the differences between these two cuts of beef.

Flap Meat is Great for Stir Fries

I like to take this cut and slice it into this strips, against the grain, for use in stir fries.

Sliced Flap Steak for Stir Fry

You can season the steak with salt and pepper then sear it in a wok with some peanut oil.

Throw in some broccoli, mushrooms, onions and peppers along with some cornstarch, soy sauce and a dash of sesame oil and you will have a quick and easy weeknight dinner that tastes amazing!

Beef and Broccoli Stir Fry