To cut the iceberg lettuce into wedges, remove any loose leaves from the outside. Then, cut the head of lettuce in half. Remove the core of the lettuce and cut each half in half again to have 4 equal-sized wedges. To wash, rinse the outside of the head of lettuce under water, carefully loosening the leaves of lettuce to allow water to wash the inside as well. But make sure to keep the wedge in tact as much as possible!