[scott_karana]

"Sealing in the juices" is definitely false, but a hot sear to cause the Maillaird protein reaction is important if you want to have the distinctive "traditional" steak taste.

[joshu]

The more important question for sous vide: Sear before or after vacuuming? Or both?

[scott_karana]

Dave Arnold tested this, and preferred searing before and after cooking. :)

http://www.cookingissues.com/primers/sous-vide/purdy-picture...

[alilja]

Definitely after. Cooking denatures the myosin and releases water; a seared steak soaking in water isn't going to have the kind of texture you'll get (and want!) from the Maillard reaction.

I guess what I mean is that it'll taste fine but the texture won't be quite there.