The Scandinavian cure for salmon of dill, sugar and salt is now almost as well known to us in this country as smoked salmon. Less well known is just how good it is with other oily fish, particularly mackerel. Mackerel is a cheap fish at any time of year, but in harbour towns in the summer months the fishermen, and even the fishmongers, are often practically giving it away. That’s a good time to make a large batch of gravad lax (which, incidentally, freezes well when finished).
I have read many recipes for the cure, and the ratios of sugar, salt and pepper vary hugely – from twice as much sugar as salt to twice as much salt as sugar. I tend to use a bit more sugar than salt but I don’t usually measure accurately. The quantity of coarsely ground white and/or black pepper, on the other hand, is fairly consistent: about one-tenth the combined weight of salt and sugar. As for the dill, I simply pile in as much of the finely chopped fresh herb as I can lay my hands on – usually between a fifth and a third in volume. The quality of the dill is more important than the quantity. I find the ‘growing pots’ in the supermarket have been forced too hard in heated greenhouses, and have a very feeble flavour. If you don’t have a good herb supplier, it’s well worth growing your own dill. Dried dill can be used in emergencies.
Ingredients:
about 10 very fresh mackerel
For the cure:
about 100g caster sugar (golden caster sugar for preference)
about 75g coarse salt (i. e. crystals or flakes)
about 15g coarsely ground black or white pepper, or a mixture
a large bunch of dill, coarse stalks removed, finely chopped
For the accompanying sauce:
4 teaspoons English mustard
4 teaspoons golden caster sugar or light brown sugar
2 teaspoons wine vinegar
6 tablespoons crème fraîche
2–4 tablespoons chopped dill
The quickest way to prepare the mackerel is simply to take one fillet from either side of an ungutted fish, slicing from head to tail as close as possible to the backbone, piling up the fillets on a plate as you go and discarding the heads, guts and skeletons. A slightly more skilful but less wasteful procedure is to cut off the head and slit the cavity to remove the guts. Then run the knife in a continuation of the belly slit to the tail of the fish. Turn the fish belly-down on a board and press firmly on the backbone with the base of your palm, flattening out the fish. Turn it over again, so the skin is facing down and carefully tease out the whole backbone with your fingers, using the point of the knife to cut away the flesh should it start to tear away with the bones. This technique needs practice, and is almost impossible with very fresh fish as the backbone is exceedingly reluctant to leave the flesh. Successfully executed, however, it does leave you with very neat double fillets, and almost no waste. Anyway, the filleting is the hard part; the rest is easy. In a non-metallic bowl, thoroughly mix together all the ingredients for the cure. Sprinkle some of the cure lightly over the base of your chosen box and place the first layer of fillets (single or double), skin-side down, with the thin edges just overlapping. Then sprinkle another layer of cure over, slightly heavier this time. Place the next layer of mackerel skin-side up and sprinkle over another layer of cure, then place the next layer skin-side down etc. The final number of layers depends on the size and shape of your box. It feels tidy to finish on a layer skin-side up but it really doesn’t matter.
Place a board inside the box on top of the final layer and weight it down with a couple of bricks, storage jars or whatever comes to hand. Remember that the box is going to leak, and you want to catch the leakage, so place it on a non-metallic tray. Leave in a cool place, such as a cellar, larder or fridge. Once a day, baste the mackerel by removing the weights and board and spooning over the liquid that has accumulated in the tray. Then replace the board and weights. You can eat the gravad max after 24 hours, but 72 is best. Remove the board and lift out the fillets carefully, one at a time. There is no need to scrape off the sticky dill fronds. Place each fillet skin-side down and cut into 3 or 4 slices with a sharp knife; with the blade at an angle you should be able to lift each piece away from the skin beneath.
To make the sauce, mix the mustard, sugar and vinegar together until thoroughly blended, then mix in the crème fraîche, followed by the dill. Serve the mackerel pieces piled roughly in the centre of a plate, surrounded by a few dressed salad leaves. Pass the sauce around and have plenty of brown bread and butter, or rye bread, to hand.
Variation: Traditional gravad lax
Traditional gravad lax using salmon, sea trout or large trout is made in exactly the same way, except that instead of layers of fillets you use 2 large fillets, skin-side out, cut-side in, to make a sandwich, with plenty of cure underneath, in the middle and on top. Press under a weighted board and baste in the same way but leave for rather longer: 5–7 days is ideal, 3 days an absolute minimum. Serve in the same way as gravad max.