One of the joys of this is how easy and quick it is to make. If you're having people over to dinner midweek, you could make this as a first course before a plain roast chicken and provide a full-on dinner with next to no effort.
You may need to be rather brutal with the lettuce as you tear the leaves off to provide the edible wrappers for the beef, which is why I specify one to two icebergs. If you want to perk the leaves up a little, making sure they curve into appropriate respositories for later, leave them in a sinkful of very cold water while you cook the minced beef, then make sure you drain them well before piling them up on their plate.
Recipe posted by Nigella