Agreed, but if you did it right (that is, heat the meat through and through at the correct temperature[0]), really you shouldn't sear it for more than 15-20 sec

Agreed, but if you did it right (that is, heat the meat through and through at the correct temperature[0]), really you shouldn't sear it for more than 15-20 seconds on both sides. The meat is already done, searing is just for the Maillard reaction creating a browned crust on the outside, adding flavour. Any additional heating beyond that just increases the size of the transition between (hot) brown crust outside and (less hot) perfectly done meat inside, and it is that transition layer that makes a steak tough. Which is exactly the (somewhat) hard thing about cooking a proper steak, the very thing you're trying to solve with sous vide. That is the reason why they sometimes attack a sous vide steak with a butane torch. It's not only because it's cool :) [0] 53 degrees Celsius is for rare steak. Rare should not be "undercooked" (flesh proteins denature at about 50C) and with sous vide you can make sure this is indeed the case.