How to Sous Vide Flat Iron Steak

Flat iron steak is one of the newer cuts to become mainstream. Cut from the shoulder area, it used to be considered a waste cut because it was too full of connective tissue to eat. However, experts have learned how to cut in a way that removes this connective tissue to reveal edible meat that’s flavorful and, when cooked correctly, tender.

Sous vide helps get flat iron steak to an ideal tenderness by cooking it at a consistent temperature in water. Learn how to sous vide flat iron to get these delicious results to your table. 

Tips for Flat Iron Sous Vide

Selecting the Right Cut

How do you choose quality flat iron steak? First, look for Premium Angus, USDA Prime, or Wagyu selections. These labels indicate the highest quality steaks you can buy based on marbling and overall quality. Also, find flat iron steaks labeled as wet-aged or dry-aged, a process that allows steaks to age over time in a controlled environment to enhance their texture and flavor. We have aged, high-quality flat iron steaks available for ordering online at Chicago Steak Company.

Opt for flat iron steaks that are uniform in thickness. This ensures that the steak cooks evenly during the sous vide process. Steaks with uneven thickness may result in some parts being overcooked while others are undercooked.

Trimming the Steak

Before seasoning and vacuum sealing the flat iron steak, trim any excess fat or silver skin from the surface of the steak. This ensures that the seasoning can penetrate the meat evenly and prevents any undesirable chewiness.

Vacuum Sealing

Ensure the flat iron steak is placed in a single layer inside the vacuum-sealable bag, with no overlapping pieces. This allows for even cooking and ensures that the steak maintains its shape during the sous vide process. Remove as much air as possible from the bag before sealing to maximize contact between the steak and the water.

Pre-Searing or Post-Searing

Pre-searing the flat iron steak before vacuum sealing can enhance flavor and create a deeper caramelization on the surface of the meat. Alternatively, you can opt for post-searing after sous vide cooking to develop a golden crust. Experiment with both methods to see which you prefer.

Always Check with a Meat Thermometer

Your final steak temperature should reach between 130°F-135°F for medium-rare. It’s important to remove the steps from the heat source when they are about 5 degrees F below your desired final internal temperature as the steaks continue to cook while they rest. Use the following chart as a guide for each level of doneness. 

Doneness Level	Description	Remove Steak From Heat Source at	Desired Final Internal Temperature
Rare	Red center, very juicy	115-120°F / 46-49°C	120-125°F (49-52°C)
Medium Rare	Pink center, warm and juicy	125-130°F / 52-54°C	130-135°F (54-57°C)
Medium	Pink center, slightly firm	135-140°F / 57-60°C	140-145°F (60-63°C)
Medium Well	Slight pink center, firm	145-150°F / 63-66°C	150-155°F (66-68°C)
Well Done	Brown throughout, very firm	155°F / 68°C or lower	160°F (71°C) or higher

Slice It the Right Way

Many people prefer to slice flat iron after cooking it. If you choose to do so, be sure to cut it correctly. The right way to slice flat iron is against the grain, meaning that your knife should cut in the opposite direction as the lines that run through the steak. Start slicing only after you’ve allowed the steak to rest for 5-10 minutes to allow the meat to reabsorb its juices.

Essential Equipment

Sous Vide Precision Cooker

This is the core piece of equipment for sous vide cooking. A sous vide precision cooker heats and circulates water to maintain a precise temperature throughout the cooking process. There are various models available, ranging from immersion circulators to water ovens. Choose one that fits your budget and cooking needs.

Sous Vide Container or Pot

You’ll need a container or pot large enough to hold water for sous vide cooking. Many people use a dedicated sous vide container, which is designed to hold a sous vide precision cooker securely. Alternatively, you can use a large pot or plastic container, as long as it’s heat-resistant and large enough to accommodate your steak and immersion circulator.

Vacuum-Sealable Bags or Zipper-Lock Bags

You’ll need food-grade bags suitable for sous vide cooking. Vacuum-sealable bags are designed for use with vacuum sealers and provide a tight seal. Alternatively, you can use sturdy, food-grade zipper-lock bags for the water displacement method.

Sous Vide Weights (Optional)

To prevent floating and ensure that the steak stays fully submerged in the water bath, you may need sous vide weights. These can be specialized weights designed for sous vide cooking or simply heavy kitchen items like ceramic tiles or stainless steel utensils.

Sous Vide Flat Iron Recipe

Ingredients:

• 1 ½ – 2 pounds of flank steak
• Salt, to taste
• Pepper, to taste
• Optional: minced garlic, fresh herbs (rosemary, thyme), olive oil

Instructions:

1. Fill a sous vide container or a large pot with water. Attach your sous vide precision cooker and set the temperature according to your desired level of doneness. For flat iron steak, 130°F (54°C) for medium-rare or 135°F (57°C) for medium is recommended.
2. Season the flat iron steak generously with salt and pepper. Optionally, you can add minced garlic, fresh herbs, or a drizzle of olive oil for extra flavor.
3. Place the seasoned flat iron steak in a vacuum-sealable bag or a sturdy, food-grade zipper-lock bag. Remove as much air as possible from the bag using a vacuum sealer or the water displacement method (submerge the bag in water, leaving the top open, and seal the bag once most of the air is removed).
4. Once the water bath reaches the desired temperature, carefully lower the sealed bag into the water. Ensure the steak is fully submerged. Cook the flat iron steak in the sous vide water bath for 2-4 hours. The longer cooking time will result in a more tender steak, but even a couple of hours will yield excellent results.
5. After sous vide cooking, remove the steak from the bag and pat it dry with paper towels. Preheat a skillet or grill over high heat. Sear the steak for 1-2 minutes on each side until a golden crust forms. This step is optional but adds additional flavor and texture to the steak.
6. Once seared (if desired), transfer the flat iron steak to a cutting board and let it rest for a few minutes. This allows the juices to redistribute evenly throughout the steak. Slice the steak against the grain and serve immediately.

Sous Vide Flat Iron Steak FAQ’s