Recently I had the opportunity to buy a whole cod (or "Skrei" in Norwegian, for the spawning Atlantic Cod that migrates great distances) of about 4.5 kg (head not included). This fish is only caught during the migration season, i.e. from January to April, off the Lofoten archipelago in Norway. Fishing Skrei is strictly regulated.
You can read stories about how Skrei is caught here.
I prefer buying whole fish (or chicken, fowl, et cetera) rather than pre-portioned or filleted product. There is a certain satisfaction in trying to use all of the fish.
With this particular catch I wanted to have some nice fillets to freeze for later, make a fish stock and use the thinner fillets for a classic fish and chips.
Filleting a (round) Fish
The first question is how to fillet (any round) fish. There are only two requirements: an understanding of the bone structure of the fish, and a good filleting knife (meaning sharp and flexible).
Just to the left or the right of the back fin, start cutting, using long knife strokes and leaving behind all hesitation, along the back bone. With every cut, more of the side will come off.
Continue on until the whole side has come off. Repeat for the other side. Now the part of the sides nearest the fish's head is thickest. Starting at that end, cut of pieces of about 150 gr (5.5 oz.). Assuming you will not want to unthaw all fillets at te same time, using freezer bags, pack fillets two by two and freeze. In my case, I ended up with 8 great fillets. And yes, I left the skin on.
The thinner parts of the sides are great for fish and chips. First, take off the skin. Place the remainder of the side skin-down on a cutting board, hold at the thinnest edge, holding your filleting knife still at a 45 degree angle, and start wiggling the side toward you. The knife will nicely separate the skin from the meat. Cut the meat into equal size bits and pat them dry with some kitchen towel, if necessary.
Now you could deep-fry fish in vegetable oil (classic method) or just fry in butter or oil in a skillet. Either way, the breading part is essential for the fish.
Take out three shallow bowls. Fill the first one with enough flour to thinly coat all pieces of fish. Break two eggs into the second bowl and whisk them loose. Fill the third bowl with bread crumb. My favorite are Panko-style Japanese bread crumbs.
This is the moment when you will have to get your hands dirty.
First of all, make sure to melt a nice knob of butter in a skillet.
One by one, take the pieces of fish, dusting with flour in the first bowl, covering with the egg mixture in the second and finally coating with bread crumb in the third bowl. Now place in the skillet. Repeat until done.
In the skillet, after a minute or two, turn over the pieces of fish when they take on this nice golden color. Take out and drain on a piece of kitchen towel.
Serve with your favorite fries and sauce. Mine would be tartare sauce.
If you are in a rush, start with mayonnaise. If you have a little more time, first make your own mayonnaise with a few egg yolks, a teaspoon of Dyon mustard and a spoonful of vinegar, and freshly ground pepper. In a blender, blend until the mixture thickens; then slowly add vegetable oil, such as rapeseed oil, until the mixture does not seem to be able to absorb any more oil.
The other ingredients of a tartare sauce are chopped capers and gherkins (this is the proper name according to Brits, but called pickles in the United States), flat-leaf parsley and dill and a very finely cut half of a shallot. Mix together and season with more freshly ground black pepper, salt and lemon juice.
So, at this point we have nice cod fillets in the freezer and fish and chips ready to go.
With the fish bones, the skin, fins and (if your fish came with it) the head you can make a nice fish stock that you could use for a fish soup, or a seafood risotto.
Put the fish parts in a large pot, add enough water to ust cover everything, and add aromatics. I always use a few bay leaves, about 10 juniper berries, some black pepper corns, a shallot (unpeeled and cut in half).
Add other aromatics that you may have in stock. A celery stick, a carrot, spring onion.
Bring to a boil and keep around boiling temperature for 30 minutes (longer will make the stock turn rather bitter). During this time, foam will appear on the surface. Skim this off for a clearer stock later. After 30 minutes, using a large sieve to separate the solid parts, pour the mixture into another bowl or pan. Discard the solids. Optionally, filter the stock through a mousseline cloth to clarify the stock.
Clean out the original pan, pour the stock into it and bring back to a boil to reduce the stock until it has the strength and taste you prefer. Cool down and store in a glass or plastic container with an airtight seal. You can keep the stock in the refrigerator for several days.