Leek comes from the same family as onion and garlic.
Leeks have a strong flavour, though not quite as intense as onion or garlic and is a delicious vegetable cooked as it is, or when used to intensify the flavours of a dish (much like you do with onion).
Our dired leek has a richer, more concentrated flavour and adds a wonderful flavour to homemade burgers/sausages, gravy, soups, stews and mashed potato.