A specialty grocery store recently started to sell bacalhau (heavily salted cod fish). I am guessing that a recipe I have for baked codfish would work. Since it is so heavily salted, what should I do to prepare it for cooking?
Basically it depends on how much salt (not how little water) there is in the fish. Here in Galicia and northern Portugal we usually soak it for 12 hours or so, changing the water once or twice. That will yield a slightly salty and tangy fish. If you don't like the salty edge and prefer it blander, soak it for 18 hours or so.
This answer is useful in the case you do not have much time (12 hours, or even days) to let the cod fish soak in water (put water, wait, change water, repeat). There is a nice trick to prepare it in less time.
Boil it with vegetables. Just that: put the cod fish and vegetables in water and boil them. One particular good vegetable at absorbing the salt is cauliflower. Well, actually, don't do this right away with the super-salty cod fish, it is worth to just soak it a few times with warm water (no waiting needed).
The boiling time depends on your taste. The longer the less saltier. After boiling it, in case it was not for long long time (i.e., the vegetables still have nice consistency), you can actually eat the vegetables.
One great way to do this is by adding vegetables that would complete the dish, so it is two in one, e.g., cauliflower, potatoes, broccoli, chickpeas (garbanzo beans). Enjoy.
Depends on the dryness of it. Sometimes it's completely dessicated, which means you need to soak it for a couple of days, changing the water frequently.
Sometimes it's a bit moist and spongy, in which case you can shorten the soaking to about 24 hours, again changing the water frequently.
Or, you can just buy fresh cod.