This knobbly vegetable is memeber of the celery family. It has a distinctive flavour much like celery, but a bit milder.
It can be eaten raw and makes a nice crunchy addition to salad. However, it is most popular cooked in soups or diced and boiled in a potato salad, where it gives a complimentary flavour.
Celeriac bulbs should be purchased reasonably small. When peeled and cut they need to be used immediately or put into a bowl of water and lemon juice because they discolour quickly when exposed to light.