Sous Vide Flank Steak
Tender, succulent, flavorful meat cooked to perfection and drizzled with a rich, velvety sauce is guaranteed with glazed Sous Vide Flank Steak. Impress your guests!
I’ve made flank steak using a sous vide cooking method (water bath) many times, but this time I decided to experiment on two things: thickness of the meat and marinating. Here’s what I found.
Tips on Thickness for Sous Vide Flank Steak
For the first experiment, I had no choice in the matter. I unfolded the certified angus beef flank steak that I purchased in a package and discovered it was only 1/2 inch thick! Grrr. I thought for sure it would not work with the sous vide method. That it would not achieve a medium rare cook. And, even if it did, it would not maintain the temperature when I grilled it for browning. Well, big surprise – I was able to do both.
I had attempted to “correct” the thinness of the meat by putting half the meat in a single layer as usual in the vacuum sealed bag and the other half in a double layer. My hope was that the double layer would act as a thicker steak and achieve the medium rare I was after. My correction wasn’t necessary.
The double layer seemed to make no real difference – both options were the same medium rare. When sliced on an angle, the temperature of the flank steak was a perfect medium rare.
Bottom line: Both thin or thick flank steak will work great with sous vide cooking.
I admittedly did not grill the flank steak as long as I would have liked for a darker finish. You can, however, correct for that by flash cooling the meat after the sous vide process. See make ahead instructions.
To Marinate or Not?
The second experiment was marinating the meat before plunging it into the sous vide machine. Many experts say it’s not worth it or it can ruin the meat. I don’t know if the marinating would work on any protein, but it did add excellent flavor to my flank steak.
I can only tell you that we had a superb meal that night. The meat was melt in your mouth and tasted delicious despite the thin cut.
Tailor To Your Taste
- The glaze adds extra flavor. You can glaze the meat before grilling, after grilling or use it as a drizzle after slicing.
- Use your favorite marinade/glaze instead of the one in the recipe, but avoid fresh onions and garlic during the sous vide cooking.
- Make half the marinade only, skip the glaze portion and used the sliced flank steak for fajitas, sandwiches or in tacos.
- Use the marinade during cooking, but skip the 4-24 hour pre-marinating period. The flavors won’t be as deep, but with the glaze, the flank steak will still be excellent.
- Make the glaze and sous vide the flank steak up to a few days ahead. Once the cooking process is complete, plunge the bag with the meat into an ice water bath to cool completely (about 20-30 minutes if meat is not too thick) and refrigerate.
- Because flank steak is fairly thin, you can then directly grill (or sear) the steak for a couple of minutes per side, glazing the steak or drizzling it with the glaze once sliced.
- Do not put the flank steak in the fridge directly from the sous vide water bath.
If you’re looking for general tips about sous vide cooking regarding preparation, set up, temperature, timing and finishing, check out our best sous vide recipes and tips.
And if you love flank steak, but don’t have sous vide equipment, try our marinated flank steak.
How to make sous vide flank steak
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Sous Vide Flank Steak
- Sous Vide equipment
- 1 1/4 pounds flank steak about 1/2-1 inch thick
- salt and pepper
Marinade and Glaze
- 1/4 cup olive oil
- 1/4 cup balsamic vinegar (good quality)
- 1 tablespoon grainy old fashioned mustard
- 1/4 teaspoon garlic powder
- 1 teaspoon dried rosemary
- 1 teaspoon dried thyme
- HEAT THE WATER IN SOUS VIDE MACHINE: For this recipe, I used a Sous Vide Supreme machine. Fill the sous vide machine/vessel about 3/4 full with water. Set the temperature to 132F for medium rare (or according to your machine guidelines). The water will take about 15 minutes to reach the correct temperature (or less if you start with warm water).
- MAKE MARINADE/GLAZE: Put all marinade/glaze ingredients in a small saucepan. Stir to combine. Pour half the marinade into a seal-able ziploc bag. Leave the other half in the saucepan to make the glaze.
- MARINATE FLANK STEAK: Sprinkle the flank steak with salt and pepper. Poke it all over with a small sharp knife to let the marinade seep in. Place in bag with marinade. Seal bag and massage bag to spread marinade all over meat. Let meat marinate for 4 -6 hours (or up to 24 hours) if you have time.
- VACUUM SEAL MEAT: Cut flank steak in half if too large for one vacuum seal bag. (Alternatively, use one large ziploc bag and use water displacement method to submerge in sous vide). Fold over a flap on 1 (or 2) vacuum seal bags. Remove flank steak from marinade and pat lightly with paper towel to remove excess moisture. Place in vacuum seal bag. Unfold flap and seal bag(s) with vacuum sealer.
- SOUS VIDE FLANK STEAK: Plunge bag(s) into pre-heated water bath. They will sink to the bottom. Cover machine (if applicable). Cook in bath for 1 1/2 hours if flank steak is 1/2 inch thick. If meat is thicker, cook for 2 to 2 1/2 hours.
- FINISH GLAZE: While meat is in sous vide bath, bring reserved marinade in saucepan to a boil, lower heat to medium and cook until reduce and slightly thickened. It should coat the back of a spoon.
- FINISH FLANK: To GRILL: Heat grill to high 10 minutes before flank is done. Remove meat from from sealed bag. Pat dry with paper towel. Spray with oil, sprinkle lightly with salt and pepper, grill for 1 minute per side. To FLASH FRY: Alternatively, heat 1-2 teaspoons oil in skillet to medium high flash fry for one minute per side to brown the exterior. Slice meat thinly across the grain on a diagonal, then drizzle on glaze.
- You can make the glaze and sous vide the flank steak a few days ahead. Once sous vide is complete, plunge the bag with the meat into an ice water bath to cool completely (about 20-30 minutes if meat is not too thick) and refrigerate.
- Because flank steak is fairly thin, you can then directly grill (or sear) the steak for a couple of minutes per side, glazing the steak or drizzling the steak once sliced. Do not put the flank steak in the fridge directly from the sous vide water bath.
Love your recipes!
We have done Sous Vide for years but generally do not vacuum seal marinades. Usually the liquid is drawn up and out of the bag during vacuum sealing.
Do you have any tips/ tricks to prevent this?
Lastly, I was planning on searing it in my new carbon steel pan.
I’ve read not to use vinegar based sauces as it can alter the seasoning/ blackening of the pan. Would this be the case here?
Thank you very much!
So glad you’re enjoying our recipes! I’ve given up on vacuum sealing, particularly with marinades as, you’re right, they seep out when sealing. Only the fancier more expensive vacuum sealers work well with marinades I believe. I stick to ziplocks now.
As for the pan searing, you will be drying the meat well before searing with paper towels so I don’t think that should affect your pan. If you’re worried, though, can you use a different pan? Is hate to see it get ruined. I hope that helps.
I did not have a good experience with this recipe. I made the marinade as described. I marinated it for about 22 hours. I vacuum sealed it after that. I cooked it in the sous vide bath as specified. I seared it in a cast iron pan over high heat. I can only describe it as decently flavored but super mushy. Not tender, but mushy. The meat lost all texture. It seemed to be a good cut of meat prior to and was about two inches thick. So I don’t know if I overmarinated… if I water bathed it too long… I just don’t know. The glaze helped a little. But overall, I was disappointed. I gave it to my daughter in law to serve to my 14 month old grandson, because it was that soft. (He loved it.). Any tips? We do a lot of sous vide cooking and usually, our recipes are fantastic. So we aren’t novices. Where did we go wrong?
Hi Marilyn. I’m so sorry the recipe didn’t work for you. If you only cooked the meat sous vide for a few hours, I suspect the meat became mushy from the marinade. Lower quality (overly acidy) vinegar or too long a marinating time with an acidic component can do that. Do you think that could be it? I hope it works better next time if you try it again.
Thank you Cheryl. I think that’s what it was, actually, My balsamic vinegar may have been a little old… so therefore more acidic over time. Also, I thought that was a really long time to marinate it. Will try it again and thank you for getting back to me!
Hope it works better next time Marilyn. 😊
Can you freeze glaze
You can, but may find the oil and vinegar separate which may not be that easy to blend again. A better alternative may be to store the glaze in the fridge in an airtight container or ziploc. It should last for a month or more. Hope that helps.
I have a small (1/2-3/4 lb) frozen, sealed flank steak. How long should I sous vide it?
Hi Karen, Since it’s small, usually an extra hour is needed for frozen meat. So a total of about 3 to 3 1/2 hours should be fine if it’s not too thick. Hope that helps.
The absolute BEST flank I’ve ever had. Cooked to perfection. Thank you!
Happy you enjoyed it! Thanks for taking the time to leave a comment 🙂
How does the reserved marinade make a glaze with so ,pouch olive oil..mine just separated
Sorry to hear you had trouble with the glaze. I haven’t had that problem before. You can try skimming off some of the oil before you boil it down. Or using a little less oil in the marinade. Another option is to stir in a cornstarch slurry once the glaze is boiling. That will thicken it and pull it together. A slurry of 1/2 tsp cornstarch mixed with a tbsp water should work.