Cooking fish can be a very a misunderstood thing. A lot of mongers and mothers rattle off rules of thumb that don't really do anybody anygood.
For instance, "bake for 20 minutes @ 425˚degrees". I hear this advised for almost every fish, regardless of size or shape. Though it is too hot and too long for just about any fish I'd suggest eating.
Go here for some tips on cooking codfish.
Have you ever played shuffle board at a bar? You slide a heavy metal disk down a wooden game board. The goal is to get the disc to come to a stop in just the right place. It requires a very delicate hand.
Cooking fish, or anything for that matter, is very much the same. The fish is moving down a spectrum from raw to cooked, and the idea is that the fish stops cooking in just the right place.
In shuffle board, you can't put too much power behind it, or it will fly right off the board every time. As well with fish, a hot oven is bound to push you over the edge. To get the fish to just the right place, you have to give it a gentle push - at a gentler heat (325˚F) and pull it out of the oven at the right moment, such that the cooking of the fish slows to a stop hen it is cooked, bu still moist and delicious.
Where's that place? It depends on the fish. The size of the piece and the width. Will you sear it first?
Just give yourself some leeway - pull it from the oven on the early side - you can always cook it more. For flaky fish, you can give it a firm but gentle press with a finger, feeling for the flakes to separate slightly. For a fat piece, lightly squeeze the sides. They should look opaque and feel firm. Also, expect more massive pieces of fish to carry over more.
Here's a piece on how to cook whole fish and know when it's done.
If you see white stuff seeping out of your fish — you've gone WAY too far. That shouldn't happen.
ALSO, I say this all of the time, but it holds especially true with fish — You have to buy the best you can find. Fish is not the place to try to save a few bucks, you need to find the best. No amount of finesse or know-how will set bad fish straight.
Another issue that plagues fish cooks is sticking stubbornly to stainless steel. This video shuld help you sort that out a little.
Mediterranean Style Fish with Almonds and Dried Fruit
2 lbs sturdy fish, cut into 1 inch cubes (swordfish, mahi mahi, halibut, tuna, etc)
1 Shallot, sliced thinly
1/2 roasted almonds, roughly chopped
1/4 cup dried fruit (cranberry, cherry, raisin, etc.
One Lemon, zest peeled-pith removed - juice reserved
1/4 cup chopped parsley
Nice extra virgin olive oil
1. Heat a heavy bottomed skillet over medium heat.
2. Toss the fish with salt, freshly ground black pepper and enough oil to lightly coat.
3. Working in two batches, sear the cubes of fish on a few sides. It's bettaer not to be OCD about hitting each side because it will overcook the fish. Four sides is enough.
4. Set the fish aside and in the same pan, add a little oil to lube the surface and drop in the sliced shallot and cook for one minute. Add the lemon peel, almonds, and dried fruit. Stir well to combine.
5. Kill the heat and return the fish to the pan and toss well. Squeeze over the lemon juice and finish with a few generous tablespoons of extra virgin olive oil.
I actually just used a nut mix for this. It was perfect.
Taste for seasoning. Make sure it has enough salt. This dish should also be nice and tangy, so another lemon's worth of juice may be in order.
This was yummy!