Lightly fry 8 oz / 230 g sliced field mushrooms with two finely chopped shallots in a little olive oil until soft. Raise the heat and allow any liquid from the mushrooms to evaporate, then season to taste, allow to cool, and mash together with 3 oz / 85 g butter. Sandwich this thickly, garnished with some flat-leaved parsley, between thick slices of crusty white bread. It is also good in pitta bread. Try adding pitted black olives, chopped spring onions and finely sliced tomato.