After having cooked sous-vide for six years, I still discover some improvements now and then. Until recently, when cooking beef sous-vide I would usually choose as low a temperature as possible, and then cook long enough for the meat to become tender. This has as an advantage that the beef retains as much juices as possible, because at higher temperatures more juice is lost by contracting muscle fibers (click here to read more about this). This way you can turn even very tough cuts into something that has the texture and color of a medium-rare fillet steak. Examples are beef short ribs or beef brisket for 48 hours at 57C/135F, flank steak or skirt steak for 48 hours at 55C/131F, blade/flat iron steak for 12 hours at 55C/131F, and oxtail for 100 hours at 60C/140F. Although beef cooked this way is amazing because it has the same tenderness as fillet steak but much more flavor, and there is no way besides sous-vide to achieve this, sometimes it smells a bit funky and some people don’t like it because it is different from what they are used to.
Instead of steak-like texture I also use sous-vide to cook beef with a flaky texture. To get a flaky texture I sometimes used 62C-63C/143-145F for 48-72 hours for chuck or (veal) osso buco, or higher temperatures like 82-88C/180-190F for 5-10 hours to get the same result as a stovetop braise, but with less effort and less risk of inconsistent results. This was all based on my own experimentation as well as Modernist Cuisine and various online sources including Jason Logsdon. When going from 55-57C/131-135F to 62-63C/143-145F I noticed such a large loss in juiciness that I never thought it would be worth trying anything higher than that, as I thought it would just take more time and achieve a similar result as going up to 82-88C/180-190F for a shorter time. That turns out to be wrong! It turns out that 74C/165F for 18-24 hours gives the same tenderness and flaky texture as going up to 82-88C/180-190F, but the beef ends up more juicy. And because of this temperature the connective tissue dissolves better, the meat is even more succulent than at 62-63C/143-145F. And so now 74C/165F is my new favorite temperature to get a flaky texture. It doesn’t only work for beef, but also for pork, lamb and turkey.
For this post I have tried cooking beef flank steak at various temperatures: 55C/131F for 48 hours, 60C/140F for 24 hours, 74C/165F for 24 hours, and 88C/190F for 7 hours and compared the juiciness and texture. The cooking times are based on my experience and all yield beef that is tender. I measured the loss of juices by weighing the meat before and after cooking. I used the above flank steak (which is called bavette in France and the Netherlands) and cut it into 4 pieces that were seasoned with salt and pepper and vacuum sealed. It is important for flavor and succulence that the steak is nicely marbled with fat.
I labeled the bags with the cooking temperature and initial weight in grams, and cooked them sous-vide for the time and temperature indicated.
The flank steak cooked at 55C/131F for 48 hours lost 23% of its weight.
I gave it a quick sear in clarified butter over very high heat, just to give it some color.
The meat was juicy, very tender, and very tasty, with a slightly loose but steak-like texture.
Cooked at 60C/140F for 24 hours, the weight loss was 31%, so quite a bit more than the 23% at 55C/131F.
The meat was not only measurably but also noticeably less juicy than when cooked at 55C/131F, and I also thought that the texture was a bit mealy. So for the two temperatures that result in a steak-like texture, I definitely prefer 55C/131F over 60C/140F.
Going up to 74C/165F, still for 24 hours, the weight loss is 39%.
The meat had a great tender flaky texture and despite the hefty loss of juices was very succulent. It is very different from flank steak cooked at 55C/131F, but just as good, only in a different way.
The weight loss after 7 hours at 88C/190F was 42%.
This was very flaky, quite dry and grey looking, like a traditional stovetop braise. It was still tender and pleasant to eat, but not by far as good as the flank steak cooked at 74C/165F.
So in conclusion: depending on what texture you would like, my recommendations for flank steak sous-vide are:
- 48 hours at 55C/131F for tender steak-like texture
- 24 hours at 74C/165F for flaky braised-like texture
P.S. Some sources will tell you that flank steak can be cooked sous-vide for 6 hours at 55C/131F. If you do that, the meat will still be quite tough and will have to be cut very thinly across the grain. If you think the flank steak is too tender/too ‘loose’ after 48 hours at 55C/131F, you could lower the cooking time to 24 hours.
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