How to Sous Vide Flank Steak

Some steak cooking methods leave you wondering how to get a tender pink middle without overcooking the outside. Sous vide leaves the guesswork out of the equation by cooking flank steak in a water bath to allow for even cooking throughout. The result is steak cooked to your preferred doneness level without a lot of work on your part.

Want to learn how to sous vide flank steak? Read through this guide and follow the recipe and instructions below to sous vide like a professional.

How to Select the Right Flank Steak for Sous Vide

Buying high-quality flank steak at the butcher or store is the best way to get high-quality results when you sous vide. Look for steaks marked as Premium Angus, USDA Prime, or Wagyu. These are premium cuts of steak with excellent marbling and overall quality compared to more affordable cuts that can be tougher and not as flavorful.

Sous Vide Basics

Sous vide is simple once you get your setup dialed in. Flank steak loves the steady heat, but small details make a big difference in texture and crust. Use these pro moves to keep the cook clean, consistent, and steakhouse-worthy.

• Keep it flat: Make sure the steak goes into its bag in a single layer without folding it. If your flank is wider than the bag, cut it into two equal pieces so every inch cooks at the same rate.
• Give the water room to work: Don’t crowd the water bath. Leave at least an inch between bags and keep the circulator intake/outlet clear. A rack or a couple of binder clips on the pot’s rim help hold bags in place.
• Stop the float: Trapped air leads to uneven sous vide cooking. Use the displacement method to push out air, then clip a small sous vide weight to the bottom of the bag. If you don’t have a weight, you can clip a sealed zip bag filled with a little water to the outside as a counterweight.
• Control evaporation: The longer you sous vide, the more your water may evaporate, causing the steak to not remain submerged. Cover the pan with a lid and top off with hot water if needed to keep the steak submerged.
• Make-ahead like a pro: Not serving your steak right away? After removing from the sous vide cooker, shock the steak in an ice bath for 10 minutes, then refrigerate up to 3 days. When you’re ready to enjoy your flank steak, dry it well and sear it in a skillet or on the grill. 

Why Sous Vide Is Ideal for Cooking Flank Steak?

Flank steak has long muscle fibers that can make it tougher to chew than other steaks, especially if it’s not cooked with care. Sous vide takes the stress out of cooking by providing a steady cooking temperature, which helps avoid overcooking and drying out flank steak (something that can happen relatively easily if pan-searing or grilling). There are lots of reasons to use sous vide for flank steak, including:

Enhanced Flavor Customization

A sealed bag keeps all the flavors you want to infuse in your steak in one place, so they can’t escape during cooking. The aromatics and seasonings you use won’t fall off or evaporate during cooking, instead staying right up against the flank steak during the sous vide process. Be sure to use high-quality sous vide bags to ensure a leak-proof cook that locks in all your flavors. 

Unmatched Tenderness

Flank carries more connective tissue than many steaks. A controlled water bath gives those fibers time to dissolve while the steak cooks to your chosen doneness. This process doesn’t cause the outside to dry out or leave unsightly gray bands on your steak. Instead, you’ll get juicy, sliceable meat that’s perfect for fajitas, steak salads, and other yummy dishes. 

Effortless and Convenient

Sous vide does take a bit more setting up than other cooking methods, but once you’ve done it one time, you can repeat the process easily for future cooks. Once the steak goes into the water bath, sous vide becomes somewhat of a set-it-and-forget-it cooking process that you don’t have to fuss over all day. It does the hard work for you in terms of cooking the steak to the right doneness level, so you can spend more time preparing your sides or relaxing until it’s ready to enjoy.

Consistent Cooking

A sous vide bath is designed for precision cooking, meaning you won’t have swings of hot and cold temperatures like you do when using a grill, oven, or pan. Sous vide keeps every cook identical, whether your flank is thick on one end or perfectly even. You choose the doneness, and the bath holds it there. This consistency makes it easy to repeat great results for weeknights and company alike.

To Marinate or Not?

It’s completely optional to use a marinade on steak, but flank steak is one of those cuts that it works really well with. The right marinade adds flavor and helps tenderize the steak throughout the sous vide process. If you decide to use one, marinate your flank steak for at least two hours in the refrigerator before cooking, or preferably overnight. 

Temperature and Timing for Sous Vide Flank Steak

Plan on a two to four-hour window once the water bath hits the target temperature. Two hours is plenty for a standard one-inch or slightly thicker flank steak to help it cook edge to edge while remaining juicy. Go for three to four hours if your steak is thicker, you want a touch more tenderness, or you’re cooking the steak straight from the fridge. 

Just try to avoid going past four hours, if possible. Longer isn’t better with flank steak, and it can actually soften its bite a little too much to the point of making it mushy. After finishing the sous vide part, you’ll need another five minutes or so to sear the steak, and another five minutes to rest it before serving. 

Final Temperature

The final temperature of your steak should fall within the range below given for your preferred doneness level. Refer to this chart when taking the temperature of your flank steak to ensure the right cook.

Steak Doneness	Cook Temperature	Final Temperature
Medium-rare	130°F	130°F-135°F
Medium	140°F	140°F-145°F
Medium-well	150°F	150°F-155°F
Well-done	160°F	160°F-165°F

What is the Best Way to Sear Flank Steak After Sous Vide?

Sous vide cooks flank steak to the right temperature, but most people still want a crispy outer crust that adds flavor and texture to the steak. That’s what searing is for. You have two options, generally: searing in a pan and finishing off the steak on the grill. Both are excellent options, although they vary slightly in flavor and technique. 

Pan Searing

Choose the pan when you want maximum crust and control. Conductive heat from cast iron or stainless steel delivers deep, even browning from edge to edge, which pairs well with the flank’s bold beefiness. Pan searing lets you really fine-tune your timing, and you can even create a quick pan sauce using the leftover juices from the pan. Pan-searing also leaves room to add some aromatics while you sear, such as butter, garlic, or your favorite herbs, leading to a classic steakhouse finish. It’s a weeknight-friendly way to finish off sous vide flank steak in a few minutes (plus, it’s weather-proof!).

Grill Finish

Opt for the grill when you want smoke, char, and that loved outdoor flavor the grill brings. The grill also leaves aesthetically pleasing grill marks on flank steak that can help your steak stand out on a plate, if that’s the kind of thing you’re going for. You can also use wood chunks or a smoker box to infuse extra smoky flavors into the meat. Unlike a pan, a grill can accommodate multiple steaks at one time, which is ideal if you’re cooking for a large group. But the grill does take more time to set up and clean for a steak cook, and you won’t be able to make a pan sauce using steak drippings. 

How to Cook a Flank Steak Sous Vide, Step by Step

Learn how to sous vide flank steak with these step-by-step instructions.

Step 1: Preheat Precision Cooker

Fill your pot with warm water, leaving a couple of inches at the top so it won’t overflow once the steak goes in. Clamp the circulator on and set it to 130 degrees for medium-rare (or your target from the chart). Let it preheat, usually 10-15 minutes. Check that the water level sits between the unit’s minimum and maximum fill marks. Cover the pot with a lid or foil to keep the water from evaporating while you prepare the steak. 

Step 2: Season the Steak

Pat the flank steak very dry so the seasoning sticks and the crust browns later. Sprinkle salt on both sides and along the edges. If time allows, let it sit 30-45 minutes at room temperature so the salt can infuse with the steak and create a brine. Add freshly cracked black pepper right before bagging the steaks. If you’re using a marinade, skip the pre-seasoning. 

Step 3: Add Aromatics

Place the steak into the sous vide bag in a single layer (one steak per bag). Tuck in a smashed garlic clove, a small sprig of thyme or rosemary, and a strip of lemon or orange zest. You can also add a tablespoon of butter if you’d like, but keep all aromatics minimal so the beef stays front and center. If you marinate the steak, add a spoon or two of the liquid to the bag. Keep herbs off the sealing area to avoid leaks.

Step 4: Seal Bag

Fold the top inch of the bag outward before adding the steak to keep the seal line dry. Unfold, then seal with a vacuum sealer until most air is gone but without compressing the steak. Alternatively, you can use a zip-top bag, but if you do so, use the water displacement method. Lower the bag into the bath until the air escapes, then zip it shut. Wipe the seal if wet and check for bubbles along the seams. If you’re using thin bags, you may want to double-bag the steaks to prevent leaks. 

Step 5: Cook Steak

Lower the sealed bag into the 130-degree bath for medium-rare, making sure the steak is fully submerged and the circulator has space to move water. Clip the top of the bag to the pot so it stays in place. Flank steak generally needs about two hours of sous vide cooking, but you can go up to four hours for thicker pieces or a bit more tenderness. If cooking from frozen, add 30-45 minutes to the time. Cover the pot to limit evaporation and top off with hot water as needed.

Step 6: Remove Steak From Bag

Lift the bag out using tongs and transfer the steak to a rack or plate. If desired, pour the clear bag juices into a bowl to create a quick pan sauce later. Discard leftover marinade. Blot the steak dry on all sides, remove any remaining herbs, and re-season lightly with salt and pepper. Let the steak air-dry for a couple of minutes while your pan or grill preheats. 

Finishing a Sous Vide Steak on the Stovetop

This is one of the more popular methods of searing sous vide flank steak because it’s relatively quick and you only need a pan and some oil to do it. 

Step 7: Preheat a Cast Iron or Stainless Steel Skillet

Choose a pan that can comfortably accommodate your steaks, leaving a little bit of space around each one to sear. If you don’t have a large pan, you may need to work in batches. Set a heavy skillet over medium-high heat with a drizzle of oil. Give it a solid 2-3 minutes to fully heat the oil and pan, as a properly preheated pan will keep the steak from sticking and can help build more even color. 

Step 8: Start Searing

Pat the steak completely dry again with paper towels. Lay the steaks on the pan using tongs, and let the crust form for 60-90 seconds or until a golden-brown crust forms. If you used a sweet marinade, watch closely, as sugars can cause a quicker sear. 

Step 9: Add Aromatics

Once the first side shows good color forming, add in a tablespoon of butter along with a smashed garlic clove and a sprig of thyme or rosemary. Be sure to use a butter that can withstand high heat, like ghee or clarified butter. Tilt the pan and spoon the melting butter over the steak for 20-30 seconds. This keeps flavors infusing into the meat while it cooks and adds a smooth, buttery finish. 

Step 10: Flip and Repeat

Flip with tongs and sear the second side 60-90 seconds, basting lightly again with the butter mixture. Your goal is color and texture, not more internal temp, since the steak is already at target from the bath. If the pan has hot and cool zones, chase the hotter spot for even browning. 

Step 10a: Torch if Desired

A kitchen torch can deepen crust without extra pan time, so consider using one if your steak needs a little extra browning but without more cooking time. Dry the surface of the steak, then hold the flame 2-3 inches away and sweep in smooth, quick passes for a few seconds per area. Keep the flame moving to avoid soot or a fuel taste. Aim for a golden-brown exterior. 

Step 11: Get the Edges

Stand the steak on its sides with tongs and brown the edges in the pan for 10-20 seconds per section. Or, if using the torch, point the torch toward the edges while you hold the steak on its side using tongs in your other hand. Focus on the fat seams and any thicker ends so the texture matches the faces. Rotate the steak as you go to get all edges evenly. 

Step 12: Rest and Re-Crisp

Set the steak on a wire rack for 3-5 minutes to allow the juices to settle. Sometimes, the surface may soften a bit while the steak rests. If that happens, you can re-crisp the steak for 10-15 seconds in the pan or with the kitchen torch just before serving. Then, slice thin against the grain at a slight angle, and finish with a pinch of salt and a drizzle of the aromatic butter from the pan. 

Finishing a Sous Vide Steak on the Grill

Alternatively, you can use a grill to finish off your sous vide flank steak. Here’s what to do. 

Step 7: Light the Grill

Clean and oil the grill grates to prevent sticking. Then, set up a two-zone fire if using a charcoal grill, making one side blazing hot for searing and the other side cooler to help control your cook. For a hint of smoke, add a small wood chunk or smoker box as the grill heats. Have long tongs, a clean platter, and a dry towel ready at the station.

Preheat the grill to high heat. Set a gas grill to 450-500 degrees for about 10-15 minutes, while the charcoal in a charcoal grill should turn ashy before grilling.  

Step 8: Sear the Steak

Pat the steak completely dry on all sides using paper towels. Sear over direct heat for quick color, 60-90 seconds. If you want cross-hatch marks, rotate the steak a quarter turn midway through searing. If the grill flames get too high, move the steak to the cooler side of the grill until they soften a bit. Flip the steaks over to the other side to repeat the searing process for 60-90 seconds. 

Step 9: Serve

Rest the steaks for 3-5 minutes on a clean rack or plate. Slice the steak thinly across the grain with a sharp knife. Sprinkle salt over the steak just before serving. If you’d like, add a pat of compound butter to the steak as it rests. Serve immediately after resting. 

Sous Vide Flank Steak Recipe

Serves: 2

Prep time: 10 minutes

Cooking time: 2 hours, 15 minutes

Ingredients:

• 1 ½ pounds of flank steak
• Salt
• Pepper
• Marinade (optional)
• Olive oil

Instructions:

1. Set the temperature of your water bath to 130 degrees for medium-rare. Sprinkle steaks with salt and pepper (if using a marinade, you can skip this step if you’d like). Then, add one steak to each sous vide bag. Seal the bags, removing as much air as possible.
2. Carefully lower the bags into the water so that they’re fully submerged. Cook for two hours or up to four hours, maximum. 
3. Remove the bags from the water with tongs. Carefully open each bag and remove the steaks. Pat them dry completely. Heat a skillet with a drizzle of oil. Sear steaks on each side for 1-2 minutes until golden brown. Remove from heat and rest for five minutes.

Conclusion: How to Make Sous Vide Flank Steak

You now have all the steps and tips needed to sous vide and sear flank steak for a no-fuss approach to getting just the right cook. If you’re looking for other ways to cook flank steak, we have you covered there, too:

• How to Grill Flank Steak
• Cooking Flank Steak on a Blackstone
• Air Frying Flank Steak
• How to Smoke Flank Steak
• Tips for Cooking Flank Steak
• How to Pan Sear Flank Steak
• How to Cook Flank Steak in the Oven
• How to Slow Cook Flank Steak