In his book, Baldwin gives a medium-rare temperature for fillet (or tenderloin) of 55ºC, though I note that these days the plethora of sous-vide sides tend to go for 56.5ºC for medium-rare. Personally I've found that delivers rare beef for me, though I've found Baldwin's medium-rare temperature resulted in a texture that was a little too raw-like for the children, so I've usually gone for 56ºC, which still comes out as rare for me.
The other number on the sliding-scale of cooking sous vide is actually the time you'll be cooking for/the thickness of the meat you'll be cooking... If you're going to cook for longer periods of time, you can afford to drop the temperature a little, but if you're going for a fillet of beef you can serve in 2 hours, you'd be better sticking to that higher number - the meat must have an internal temperature of 55-56ºC by the time you've finished cooking it. It can however be held for almost as long as you wish in the water.
It's still essential to brown your meat once it's been cooked, as the browning process (the Maillard reaction) adds flavour, aroma and a better texture to your finished joint. Some people sear their meat before putting it into the vac-pac, but I've never found that as successful as searing it post the water bath.
You can put any flavours you like into your vac-pac, but bear in mind that they'll be more intense than just marinading. I like to cover mine in porcini oil - because you're only using a little in reality, the expense is justified for me. Porcini oil has an additional level of umami'ness that I think works well with the seared beef - even if the texture is still quite soft, the extra meaty flavour and aroma work well with the joint. Today I've also added about a tablespoon of worcestershire sauce - hey - it was right next to the pepper and salt, and I thought it would add even more depth to the crust when I sear it.
So. My beef was cooked for 4 hours, at 56ºC. The internal temperature was correct when it emerged, and it was seared for just a few minutes on each side. The beef doesn't need to be rested in the manner of a conventional joint, so you can slice it as soon as the rest of your meal is ready* :0) Simples. Rare beef on demand...
In case rare is not your thing, here are the other (most commonly agreed) temperatures. Please do play around to find the right temperature for you! As I said, 56ºC should give me closer to medium-rare, but it usually doesn't.
Rare: 49°C (120°F)
Medium Rare: 56.5°C (134°F)
Medium: 60°C (140°F)
Medium Well: 65.5°C (150°F)
Well Done: 71°C (160°F)
- I use a chamber vacuum machine, though I find it doesn't entirely expel air compared to a commercial machine, even at 9 Bar! You can seal your bag having expelled the air using the Archimedes method, or sealing with a normal bag sealer, though again you won't expel all the air.
- Trust me, when they say you should wind back your bag to prevent cross-contamination - you actually should fold it back at least twice if you can - the number of times I've put a little drop of oil etc on the first fold is ridiculous. If anything is spilt on the upper edges of the bag, it will result in a substandard seal, and you may find your joint 'swimming with the fishes'
- You can't really do your vegetables at the same temperature, they really do require something closer to 80ºC to cook properly, however you can cook them lightly on the hob, then hold them in a vac pac bag in the water bath - I've done some carrots that way today to demonstrate... If you're going to make baby carrots, do scrape down the top of the root, you don't want grit in your vac pac. I suppose if I was super-organised I could have done the veg at a higher temperature first, and then held them at the lower temperature...
|Rare, but consistent throughout|
|Fillet of beef, sealed with porcini oil, worcestershire sauce, salt and pepper|
|The beef really does take seconds to sear, don't leave it in unattended for too long|
|The other side|
|Par-boiled baby carrots, packed with carrot tops, butter and orange juice|
|Carrots, stil al dente, though held in water for over an hour|