Sous Vide Flank Steak

This Sous Vide Flank Steak recipe is a guaranteed way of producing a juicy, tender Steak. The whole process is foolproof, so anyone can do it! Flank Steak undergoes Sous Vide cooking, then it is seared to produce a savory seasoned crust. Searing can be achieved on a grill, or stovetop with a cast iron skillet or fry pan.

So why Sous Vide Flank Steak? Flank Steak, also known as London Broil, has a lack of fat marbling and dense meat fibers making it an ideal candidate for cooking Sous Vide. Cooking it entirely on a grill or in a skillet raises the potential for the Steak to be dry and tough.

For more information on what Sous Vide actually is, please refer to my post on Sous Vide Corned Beef.

Ingredients

• Flank steak: choose fresh beef, preferably grass fed. Remove all silverskin.
• Salt and pepper: kosher salt works best as its shards penetrate meat fibers well.
• Oil: use a high temp oil such as avocado oil or olive oil (not extra virgin).

Instructions

Questions about the Preparation and Cooking of Sous Vide Flank Steak

When do I season the Steak?

Always season it prior to the putting the Steak into the plastic bag. Sprinkle salt and pepper over the steak at least half an hour before you want to Sous Vide it. Leaving the salt and pepper on for longer, will act as a dry brine, which will only make the meat more tender!

Can I add rubs, aromatics, and marinades?

Absolutely, use a dry rub, add some fresh herb sprigs or a liquid marinade to the steak and pop the steak immediately in the bag. For best results place the vacuum sealed bag in the refrigerator for 24 hours.

How long do you cook Flank Steak in the Sous Vide and at what temperature?

See the table below:

Medium Rare, Steak is red, slightly firm texture, minimal juice loss.	130 degrees F / 54 degrees C	Ready in 45 minutes	Can be held for another 3 hours in Sous Vide after cooking.
Medium, Steak has a rosy pink center, with 4 times more juice loss than Med / rare.	135 degrees F / 57 degrees C	Ready in 45 minutes	Can be held for another 3 hours in Sous Vide after cooking.
Medium Well, little pink in the center, texture is firmer, 6 times more juice loss than Med / rare.	145 degrees F / 63 degrees C	Ready in 45 minutes	Can be held for another 2.5 hours in Sous Vide after cooking.
Well Done, steak is at its firmest, center and surface are the same color (brown), maximum juice loss: 10-15 times more than a Med / rare steak.	156 degrees F / 69 degrees C	Ready in 1 hour	Can be held for another 2 hours in Sous Vide after cooking.

• What is the recommended temperature to set the Sous Vide Circulator when cooking Flank Steak? In order to preserve the meat juices, I recommend cooking it at 130 degrees F / 54 degrees C for at least 45 minutes. I cooked my 2lbs 8oz (1kg 135g) for 1 hour at 130 degrees F. I had no real noticeable meat juice loss.

What are the Downsides to Cooking Steak Sous Vide Vs Using a More Traditional Method?

There are definitely cons when choosing to Sous Vide a Steak. Here are the ones I came up with:

• Sous Vide cooking is time consuming. It requires a bit of planning. You don’t come home from work, turn on the grill and start cooking. From start to finish, the whole process will take at least 1 hour if you choose a medium / rare finish. More if you want your steak cooked further.
• Two sets of equipment are needed. One set for the Sous Vide process (the actual Sous Vide Circulator, container for hot water, lid, food saver bags, vacuum sealer). The other set of equipment is needed for the searing step (cast iron skillet or heavy bottomed frying pan or grill).
• There are two cooking steps (Sous Vide and searing) to prepare the Steak.
• Even though Sous Vide cooking is foolproof and Steak and other meats can be held in a temperature controlled water bath for several hours without continued cooking, the quality of the meat can begin to deteriorate. Do not go beyond 4 hours.

Recipe Flexibility

Use the same instructions above to make the following variations:

Sous Vide Skirt Steak

Skirt Steak is a little hard to find in the meat department of a typical supermarket, but it will appear in a butcher’s shop. Skirt Steak is flavorful but known to be on the tough side. Sous Vide cooking for this steak will minimize toughness. I recommend marinating this steak first in a bag, overnight in the refrigerator before it is cooked Sous Vide.

Sous Vide Hanger Steak

Hanger Steak is a tender cut of steak, taking second place in tenderness after tenderloin. Prepare it the same way as Flank Steak, then Sous Vide at 130 degrees F / 54 degrees C for 45 minutes.

Sous Vide Flat Iron Steak

Flat Iron Steak is similar to Hanger Steak in that it is tender but has a little more flavor than Hanger Steak. It has more marbling throughout the muscle. This addition of fat is welcome as the end result will be a flavorful, juicy, tender piece of meat. Sous Vide it at 130 degrees F / 54 degrees C for 45 minutes.

Sous Vide Teriyaki Steak

Use any of the Steaks above and marinade it first in Teriyaki marinade for about 30 minutes to 2 hours for a quick marinade time and up to 24 hours for a more pronounced flavor. Do not go beyond 24 hours as the meat will get too salty and toughen up. This rule applies for all flavors of marinade and dry and wet rubs. Marinade the Steak in a bag, overnight in the refrigerator before it is cooked Sous Vide.

Sous Vide Flank Steak Tacos

Prepare a taco seasoning dry rub, using your own blend of spices or use a ready prepared store bought packet. Rub the steak on all sides and surfaces and place in a food saver bag for at least 2 hours or up to 24 hours in the refrigerator. Sous Vide the Steak according to how well you want it cooked. Finish it on the grill or in a cast iron skillet to form a nice crust on the meat surface. Allow to rest for about 15 – 20 minutes, then slice thinly and place in tortillas. Top with diced peppers, avocado slices and cilantro leaves.

How Can I Store and Reheat Sous Vide Flank Steak?

If the Steak Has Been Cooked Sous Vide and Seared.

If the Flank Steak has undergone Sous Vide cooking and seared on a grill or cast iron skillet, then allow the Steak to cool and place it in an air tight container or better yet – another food saver bag. The best way to reheat completely finished Steak is using the Sous Vide method. Place the bag into the water bath, set the thermometer to 130 degrees F / 54 degrees C and Sous Vide for 5-7 minutes. Then allow the meat to rest. If it is the whole piece, then allow a resting time of 20 minutes if it’s a smaller individual piece (such as leftovers) then rest for about 5-10 minutes.

If the Steak Has Only Been Cooked Sous Vide.

If the Flank Steak has only undergone Sous Vide cooking, and you want to eat it at a later stage, then allow the Steak to cool in the bag and then refrigerate. Refrigerate for up to 3 days, then Sous Vide the Steak to reheat it. Prepare a water bath, set the Sous Vide device to 130 degrees F / 54 degrees C and Sous Vide for 5-7 minutes. Then open the bag and finish the Steak by searing it on a hot grill or in a cast iron skillet. Brush the Steak with oil first.

If the Steak is Frozen.

Can Steak be directly taken out of the freezer and undergo Sous Vide cooking? The answer is yes. Steaks should be in a food saver or ziplock bag not in the original store or butcher packaging. Set the temperature for how you want your steak to appear (for medium / rare set it for 130 degrees F / 54 degrees C for 1 hour 45 minutes. An additional hour is added to the cooking time as the Steak is frozen. When Sous Vide cooking is complete, continue on with the searing part of the steak by placing it on a hot grill or cast iron skillet.

Got Questions?

I’ve got answers – hopefully!

For more information on the whole process of preparing Sous Vide Steaks refer to the post from the folks over at Serious Eats.

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