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"Don't Stop The Love" Sous Vide Flat Iron Steak with Basil Tomatillo Salsa

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Recipe updated 10/23/2019

Steak should be easy and uncomplicated, but because stakes are high (pun intended) we tend to overthink thinks when cooking steak at home. The remedy is a steak seasoned simply with salt and pepper, cooked via sous vide method and then seared. The results are a perfectly cooked steak; juicy tender center and a caramelized exterior crust that seals in all that great flavor.

Disclosure: Some of the links in this post are affiliate links, meaning, at no additional cost to you,   I will earn a commission if you click through and purchase. Note any product link included is for one I’ve used on my own quite frequently.

sliced flat iron steak topped with basil tomatillo sauce

Ingredients Needed for Sous Vide Flat Iron Steak

I’m of the mindset that steak should be a 3 ingredient affair - steak, salt, and pepper. Anything more beyond your oil or fat of choice is excess and non-essential to a great steak. The hidden flavor ingredient is “temperature”.

  • Steak
  • Kosher Salt
  • Pepper
  • Olive Oil 

Sous Vide Flat Iron Steak Recipe Inspiration

This recipe came together in my mind during a trip with my daughter to my local butcher shop, Salt and Time. I had just received my new Sous Vide machine and was looking to use it as soon as possible. My daughter at the time was trying to convert me to veganism, and my best retort was I love steak.

This conversation was on the heels of our great debate at home on which album from the New Jack Swing era was best among, Bobby Brown’s “Don’t Be Cruel”, Guy’s “Guy”, BBD’s “Poison” and Keith Sweat’s “Make It Last Forever.” These albums represent the Mt. Rushmore of that era for us.

While we debated the merits of a vegan diet vs. meat I sang Keith Sweat’s “Don’t Stop The Love” as loudly and annoyingly as possible to drain out the sermon. At the butcher shop on display was the prettiest flat iron steak I had ever laid my eyes on.

Without going too far off on a tangent let me just say, hate him or love him, Keith Sweat made it okay for the 80’s and 90’s generation for hardcore fellas to drive in their cars and bump slow jams without the presence of a female. Outside of Zapp’s “Computer Love” and perhaps Whodini’s “One Love” guys couldn’t really listen to a slow jam solo or with other guys.

The boom of the 808 bass applied generously to “Make It Last” made it okay even for the most homophobic of brothers. Whether it was a Jeep or Buick Regal with Cerwin Vega house speakers in the trunk from 1988-90 it was either Keith Sweat or “Great Adventures of Slick Rick.”

What is sous vide cooking?

Sous vide is what the pros in restaurants and on cooking shows use to get you that steak cooked at the perfect temperature for uniform doneness. It achieves predictable results again and again with little effort. It’s basically cheating! There are now cost-efficient home-cook friendly sous vide tools available.

To demystify sous vide cooking - at its core it Is a process for cooking food in a vacuum sealed bag in temperature controlled water. The water stays below boil at a steady temperature based on your desired internal temperature. The cook time is longer since you’re cooking at low steady temps, but you pretty much assure yourself of not overcooking your protein. Most important to home cooks is that sous vide essentially is hands-free cooking and the natural flavors of the food are both preserved and enhanced.

What is flat iron steak

I’ve cooked ribeyes, NY strips, etc. via sous vide, but my favorite cut for sous vide is flat iron steak. Flat-iron steaks don’t get the same shine as ribeyes, NY strips, or Filets, which is perfectly fine with me because they don’t come with the same price tag. Lower in price doesn’t mean lower in quality.

Flat-iron steaks are a great value. Flat-iron is cut from the top blade part of the shoulder so it’s lean but without much connective tissue present in most shoulder cuts. Less connective tissue = more tenderness and flavor. Depending on where you are in the world you may see it by another name such as top blade steak, patio steak, butlers' steak and oyster blade steak.

whole raw flat iron steak

Where do you find flat-iron steaks

Though they aren’t popular in restaurants, you can find them in any butcher shop and definitely behind the meat counter of most super markets. 

What equipment is needed

The two critical equipment needs are a sous vide tool and a heavy duty cast iron skillet. There are several models available but the three most popular are Sansaire, Anova, and Joule. I personally use the Anova, which is built well and has a bluetooth and wi-fi. These features allow me to monitor status and control things from my cell phone. For a more detailed breakdown of the different units checkout this comparison chart.

How to cook flat iron steak via sous vide

Does it need to be marinated?

I’ve seen all kinds of recipes that involve different tricks for tenderizing steak before cooking. Marinades are the by far the most common. However, the benefit of cooking steak via sous vide is artificial means of tenderizing are unneeded. The slow steady cooking at low temperatures achieves incredible tenderness.

How do I cook the steak in a water bath?

Vacuum sealing is the most efficient approach if you have a sealer handy. But if not, you can make a simple ziplock bag work. The key is to remove as much air as possible. To this end with the ziplock approach you'll have to use water to displace the air. To accomplish this place the steak in the ziplock then submerge slowly into the water bath making sure to keep the opening of the bag above the water. As you submerge the bag the water will push the air out. Close the bag once you've submerged the bag as far as you can without water entering the bag. Once closed the bag should sink to the bottom.

vacuum sealed flat iron steak
Vacuum sealed bag

What Temperature Do I Cook Steak At?

Time and temperature vary depending on desired temperature (medium, medium-rare, well done, etc.). I’m a medium-rare type of guy so cooking the steaks at 136.5 degrees for 45 minutes nets great result.  I use those 45 minutes of uninvolved cooking to prep/cook my sides and chimichurri/sauce. The Anova site has a lot of great resources for sous vide cooking including time and temperature guides for steaks.

What are alternatives to flat-iron steaks?

Flat-iron steaks are similar to other “flat” steaks like skirt, flank, or even hanger. So if flat iron is unavailable to you, feel free to substitute any one of the three. Flank obviously will be more readily available.

Can I Sous Vide Frozen Steak?

You can easily go from frozen steak to perfect using sous vide. So don’t fret if you don’t have the time or forget to thaw your steak if it’s frozen. Sous vide cooking is a meal prep problem solver. Just remember to adjust your cooking time about an hour to account for the thawing time.

Can this be cooked without sous vide?

Flat iron is a thicker version of flank steak. This thickness is what makes it perfect for sous vide cooking, but you don’t have to buy a new sous vide cooker to enjoy this recipe. You could easily grill or broil it following the same approach in my grilled flank steak recipe mentioned earlier.

How do I get the exterior crust for my steak?

Aha! This is where the cast iron skillet comes in. Once the steak is finished in the sous vide follow the following steps for the perfect sear:

  1. Pat dry the steak with a paper towel to get rid of any moisture
  2. Let steak sit a few minutes to get to room temperature
  3. Use a pan with ample size to ensure there is no overcrowding.
  4. Get the pan as hot as possible. If skillet is smoking, this is good.
  5. Use a high smoke point oil - peanut, avocado, grapeseed or even ghee/clarified butter
  6. Sear the steak between 45-90 seconds, making sure not to move the steak around other than the flip


steak searing in cast iron skillet
Finishing the steak with a quick sear for nice external crust.

How to slice flat iron steak

Because of its similarities to flank steak, you’ll want to cut against the grain when slicing to ensure optimal tenderness. See my earlier post on grilled flank steak for a detailed breakdown on how to cut against the grain as well as why it’s so critical.

Steak cut against the grain for maximum tenderness

What type of sauce pairs well with flat-iron steak

sliced flat iron steak on white plate

Serving Suggestions

Now that the steak is done and sliced you can dive in or level this up with a killer sauce. I generally do not use sauces with my steak. It maybe from all those years working at Kraft Foods and being all too familiar with A1 Steak Sauce, but likely closer to the fact that of more of a steak purist. My lone exception is when I’m going Argentinian style and topping a nicely grilled or seared steak with a chimichurri sauce.

Key basil tomatillo sauce ingredients. Apologies, but forgot to include the all important fresh basil in the shot.

I made a basil and tomatillo based sauce in the same vein to go with my perfectly cooked sous vide steak. The steak is great alone, but the accompanying basil tomatillo salsa is also a game changer. Together, the tender, juicy beef is enhanced by the acidic and herbal salsa. The tangy tomatillos provide a nice crunch which is a good counter to the flat iron steak.

basil tomatillo sauce in a white bowl

Most of the work for this recipe comes from making the basil tomatillo sauce. By work I mean picking herbs from my garden and chopping them along with the other ingredients. The reality is you can just toss all the ingredients in the food processor/blender and let the machine do all the work.

I chose to chop manually because I tend to be a control freak for certain things and plus chopping at times can be highly therapeutic for me. Trust me when I tell you it’s a great way to work some anger out, preferably when you’re alone.

For similar recipes, try these:

Sous Vide Smoked Brisket

Sous Vide Duck Confit

Sous Vide Beef Short Ribs

Sous Vide Radishes

Coffee Rubbed Hanger Steak

If you make this easy flat iron steak recipe please come back and leave me a comment below with your feedback. Definitely take a photo of the dish and be sure to tag #foodfidelity so that I can see them.

You can also keep up with my food exploits as well as original recipes! You can find me on InstagramFacebookTwitter, and Pinterest. If you like any of the music you find on the site, visit me at Spotify to find curated monthly playlists.

sliced flat iron steak topped with basil tomatillo sauce

Sous Vide Flat Iron Steak

Simple, easy to make steak cooked to perfection via sous vide. The flat-iron steak is restaurant quality but made at home with very little involvement for a fancy date or weeknight stress break.
Prep Time: 5 minutes
Cook Time: 1 hour
Course: Main Course
Cuisine: American
Servings: 4
Calories: 471kcal
Author: Marwin Brown


  • sous vide portable cooker
  • cast iron skillet


For The Steak

  • 1 ½ pound flat iron steak
  • ½ tablespoon kosher salt
  • ½ tablespoon fresh ground black pepper
  • 1 tablespoon olive oil

For the Sauce

  • 1 small shallot diced
  • 4 cloves garlic minced
  • 2 medium tomatillos diced
  • 2 red jalapenos seeded and diced
  • 3 basil leaves chopped
  • ¼ cup olive oil
  • 2 tablespoon red wine vinegar
  • 1 teaspoon kosher salt
  • 1 teaspoon black pepper


Cooking The Steak

  • Attach the Anova Sous Vide Cooker to the container of your choice, and preheat a sous vide bath to 136°F for medium-rare
  • Season the steak lightly with salt and pepper. Vacuum seal the steak if using a vacuum sealer. Otherwise usa a ziplock bag; partially seal it removing as much air as possible, then use the water displacement method by placing the bag in the water (always keeping the opening above the water line) to push the rest of the air out before sealing it.
  • Submerge the pouch in the water oven and cook for 3 hours.
  • Remove the steak from the pouch and pat it dry with paper towels.
  • Heat cast iron skillet on high heat, add½ tablespoon oil and then sear the steak about 1 minute a side.
  • Remove the steak and let rest for 5-10 minutes. Letting the steak rest is crucial so don't skip this step
  • Slice the steak against the grain and arrange on serving plates.

Making the Sauce

  • Place all ingredients in blender or food processor and pulse to make coarse paste. Alternatively, just chop everything finely via a knife and mix well in a bowl.


Calories: 471kcal | Carbohydrates: 4g | Protein: 33g | Fat: 35g | Saturated Fat: 9g | Cholesterol: 112mg | Sodium: 1583mg | Potassium: 637mg | Fiber: 1g | Sugar: 2g | Vitamin A: 102IU | Vitamin C: 13mg | Calcium: 19mg | Iron: 5mg
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