For 4-6 people  a large piece of salmon on the bone, just over 1kg in weight, salt.  Come high summer, there is little more useful than a piece of cooked salmon in the fridge.  You can hack off a lump for lunch, or slide an elegant wedge off the bone for supper.  You can serve it with a dithering dollop of mayonnaise or a variation of perhaps with chopped green things in it, watercrass or the like.  The best method for cooking a large piece of salmon without drying it out is the simplest.  It has been used for some time, it works and it is effortless.  Wash the salmon and check that the fishmonger has removed all the scales and the blood inside.  He probably won’t have.  Even though you told him to.  Put the fish into a large deep pan.  We use a roasting tin because it is quite deep.  Pour enough water over the fish to cover it.  Use a measuring jug so you know how much you have used.  Add salt to the ratio of 50g of salt per litre of water.  It should taste stronger than seawater but slightly less salty than an emetic.  Bring the fish slowly to the boil.  It will take a while, then watch it carefully.  There should be little more than a bubble or two before you turn off the heat.  Clap on the lid, one that fits tight.  Leave overnight to cool.  The result will be a moist, but not wet, fish.  Lift out of the water, which you might as well throw away as it is too salty for stock, and carefully peel the skin off the fish.  All you need now is some sauce to go with it.  How about some quivering mayonnaise as glossy as a tart on a Saturday night?