This is a great - if somewhat counterintuitive way - to cook a whole fish. I got the idea from Hugh Fearnley Whatsisface, though it is a very old traditional way to cook a fish.
1 large (750g to 1kg) line caught wild sea bass
2 garlic cloves
500kg rock salt, 500kg fine table salt
1 sprig rosemary or lemon thyme
Dill, marjoram, black pepper, lime juice.
Place the rock salt into a bowl and add a few table spoons of water, continue to add water until the salt is easy to mold. Then lay a base of salt, slightly larger than the fish in a baking tray, sprinkle black pepper and finely chopped garlic and lay bay leaves and/or lemon thyme on the salt, lay the fish on the salt.
The next time I make this, I am going to try not using only water to bind the salt, but to use lime and lemon juice in water, to see how this affects the flavour.
In the cavity of the fish, put a couple more bay leaves, and also a sprig of rosemary. The thing to note here is that whatever flavours you put in the cavity of the fish will permeate the flesh, so you need to be careful to not overpower the fish, but you can also take advantage of this. You could put a couple of slices of lemon, or garlic, or ginger, but really, the flavour of the fish is good enough to not augment too much.
An important thing to note is that you need to tuck the belly of the fish closed, so that the salt doesn't get in and ruin everything.
Now, dampen some table salt in a bowl and add slightly more than an equal amount of rock salt and mound a complete case of salt around the fish, leaving only the head and tail uncovered.
Then put it in the preheated oven at 220C or gas mark 7, for 35 minutes.
As an accompaniment you can boil some new potatoes for 15-17 minutes, and then when they are done, drain the water and add to them some finely chopped dill, marjoram and butter and make a simple salad of torn lettuce leaves and cherry tomatoes, dressed with olive oil and lime juice .
Serve the fish whole in the salt and then crack the hard salt case, peeling away the skin of the fish with the hard salt to reveal the white flesh. You can cleave the fillets from the bone - they should slide away with ease.
The salt case gives the fish a smokey flavour of its own, and of course you shouldn't add any salt to any other aspect of the dish, though I put a couple of drops of soy on the salad.
You can make a variation of the salad dressing for the fish, with the dill, marjoram, olive oil and lime juice and pepper and maybe a few chopped capers, but it is not really necessary as the fish if cooked properly is delicious unaccompanied.
How sustainable is this dish?