To prepare the artichokes, first snap off the stalks, then peel or break away from the base the tough outer leaves until you are left with the pale inner heart. Scrape away the prickly choke and cut the artichokes into sixths. The slices will discolour, which does not alter the taste. Rub with the cut lemon if you prefer.
Heat the oil in a large heavy saucepan or frying pan with a lid,