I don't have much experience cooking with dried and salted fish, but as far as I have read traditional recipes start with a long soaking time in water (and also changing the water multiple times) to get rid of the excess salt, followed by poaching or confiting in olive oil.
I have cooked fresh fish many times sous-vide with excellent results at around 50C. I suspect due to an extensive amount of salt, probably, changing the protein structure of the fish; this temperature might not work for rehydrated and desalted fish.
As per this question confiting is covered and another recipe for confiting sous vide also suggests 65C. However in these recipes, next to confiting, the main aim is to extract the gelatin from the fish to be later used in the sauce.
However I wasn't able to find much information on replicating poaching results with sous vide.
Does anyone have experience or resources regarding cooking temperatures for rehydrated and desalted fish.
Best Answer
The purpose for salting fish is to cure it (originally for preservation). It does not need to be cooked. The reason for soaking and/or boiling salted fish is to remove the excess salt and to rehydrate the fish for consumption. Sous vide probably doesn't make sense in the preparation of salted fish, but I'd be curious how it comes out. You should soak to remove salt to taste. Be sure to taste the inner flesh when testing for saltiness.
For sous vide preparation, I would suggest soaking in cold water to remove enough salt and then cooking at a lower temperature. 50°C is a good temperature, but you can go even lower for salted fish. You might experiment as low as 40°.