First, rinse the salt cod well under running water to remove any surface salt. Then place the piece or pieces of cod in a large bowl or other, more oblong container and add enough cold water to cover by at least a couple of inches. Stretch some plastic wrap over the bowl so it’s tightly covered and refrigerate, changing the water several times, until the fish is sufficiently desalted for you, anywhere from 12 to 48 hours, depending on the type and size of the fillet. Take a nibble now and again. If the cod seems too salty, change the water again and let it sit for a few more hours. Bear in mind: You can always add more salt to the recipe later, but you can’t take any more salt away once the cod has been incorporated into your recipe.