I'm curious whether the store-labeled "sushi grade" fish, like some salmon and scallops, can be made by cooking the fish sousvide and chilling it in the refrigerator afterwards.
Sous vide is a method to bring the interior of a meat to a safe temperature before applying a quick sear to the outside. The sear is purely for flavor and texture, not food safety.
Sushi grade fish is certified to have been processed (i.e. frozen, cut) in such a way that it's edible raw. The interior of a sushi grade salmon steak should have minimal bacteria if properly handled after purchase and isn't left to sit unrefrigerated.
So, to answer your question, yes, you can sous vide the fish, but I see no benefit, not even destroy meaningful amounts of bacteria (because there shouldn't be much there to begin with).
You can make it that way, but then comes the question as to whether you are making real sushi. If it tastes good go for it. On youtube there's a fella who uses a brine before sous viding it. He soaks it for 24 hours, and this is supposed to keep the fish translucent while sous viding. I am going to attempt a modified version of this. I'm using non sushi grade salmon, and I am going to prepare it like normal sushi. I'm going to take the mostly finished roll and wrap it tightly in cellophane and sous vide at 135. There will be some white albumin visible I'm sure. I'm not going to do the full day brine, just a simple brine for an hour or two.
Then I'll take the finished roll and sprinkle on some sesame seeds and we shall see what we shall see.
If you have sushi grade I suppose their is no point in sous viding unless you want to be really safe. But in that case you could just buy regular salmon if you are going to sous vide it.
The simple answer is yes, you can cook fish labeled as "sushi-grade"...and you can use the technique of a low temperature water bath (sous vide) to do the cooking. You can cook and chill. The folks at ChefSteps (http://www.chefsteps.com/) have quite a bit of instruction on the topic of low-temp cooking. You can find specific examples for fish, particularly salmon, on their site.