This is a doddle to make and was on the table about 15 minutes after the kettle went on for the pasta. Simply saute a couple of finely-shredded leeks (the white part only - save the green tops for some soup) in a knob of butter for a few minutes to soften - don't let it take on any colour. Grate in the zest of a lemon, then the juice of half the lemon, a splosh of white wine or white vermouth and a couple of tablespoons of water. Season with a little salt and lots of black pepper, and simmer very gently whilst you get on with cooking the spaghetti, a matter of six or seven minutes. Just before it is ready, finely slice the contents of a small pack of smoked salmon - about 100g for two people. Add about 60 ml of double cream to the pan of leeks along with the salmon. Stir. Drain the pasta, reserving a cup of the cooking water. Add pasta to sauce and stir to combine, adding a little cooking water if it seems dry. If you have any chives or fresh parsley, add that too. Serve in hot bowls and tuck in! Oh, and none of this 150g of pasta for two people rubbish - we use 220g for two, or 8oz in old money. Under NO circumstances should you add parmesan to this, it will ruin it.