Cut the Capocollo into strips and cook it in a heavy-bottomed frying pan with the oil. Add the finely sliced onion and stir; when it has softened, add the broad beans, season with salt and pepper and stir again with a wooden spoon. Cover and leave to cook for about half an hour, stirring from time to time. Just before taking the pan off the heat, tear the mint leaves up by hand, add them to the broad beans, give them a last stir and serve!