Celeriac

Celeriac, or celery root, is a relative of the familiar celery plant. However, this vegetable is grown for its tasty root instead of its stalks. It has a great texture and flavor. To use, peel off the outside layer off with a sharp knife, and wash the root thoroughly (a scrub brush is useful). Grate it raw into salads or chop and boil/bake into casseroles, soups, purees, mashes, gratins or other baked dishes. If stored in a loose plastic bag in the fridge, celeriac will store 3 to 4 months!

Short article on mashed celeriac.