Leeks belong to the onion family, look a bit like a huge spring onion and have a mild onion flavor. Miniature leeks are sometimes available. Leeks have been the national emblem of Wales since 640 AD when, according to legend, the Welsh defeated the invading Saxons because they had leeks attached to their hats. The leeks prevented them from attacking each other by mistake Leeks are a very good source of fiber and a good source of vitamin A. They also provide some vitamin C, B group, iron, potassium and calcium.