Where I live, I can't buy high-quality salt cod, so I'm looking at making my own. The recipes I've seen, though, all start with fresh cod.
Since salting dehydrates the cod anyway, it seems like I ought to be able to make it from frozen cod, which is about half the cost, and available year-round here. Does this work? Does the frozen cod have notably inferior taste or texture to salted fresh cod?
You should have no problem using good quality frozen cod for salt cod. Freezing breaks up some of the tissues and changes the texture, notably making it drier as freezing drives out some of its moisture, so you might not need as much salt to dry it to the same level.
In some places the "fresh" fish you see in the store has actually been frozen for the trip before being thawed and sold for more than the same fish still frozen, so whether you'd be getting fresh cod is debatable depending on your location.
