3: Turn the celeriac round and slice off the bottom...
4: ...at least half an inch (1 cm). It is quite hard, so you will need a good large knife.
5: Stand the celeriac on the cut base and cut away a section of peel from top to bottom.
6: Turn the celeriac slightly and repeat. Peel the whole vegetable like this. Discard the peelings, preferably for compost. Wash the chopping board of any dirt left, and dry it. Rinse the peeled celeriac under running water and dry that too.
7: Cut the celeriac into four lengthways.
8: Use a small knife to remove the slightly spongy centre from each quarter.
9: Now cut each quarter into pieces of a suitable size for your recipe: simply in half for grating, or in small pieces for soup, for example.
10: Cut up all the quarters like this and your celeriac is ready.
Remarks
The fresher the celeriac, the harder it is to cut, so use a really large knife to make this easier. Once the cut surface is exposed to the air it will start to oxidise and turn brown. If you are not going to use it immediately, wrap the pieces in plastic film and refrigerate, or put them in cold water with the juice of a lemon or, better still, a pinch of vitamin C powder.