To get to the “heart,” or bottom, of an artichoke, use a very sharp knife to cut off most of the leaves and trim around the solid core attached to the stem. This part forms a concave well in the center that is filled with fibrous, inedible material (“choke”), which can be scooped with a spoon. Cleaning artichokes is especially easy after they have been cooked in water with lots of lemon juice in it.