We actually shave it very thinly on a mandoline and add it to salads. It is absolutely delicious raw.
If I am making a celeriac puree, I cut it with potatoes so that it has a better body and the flavour is a bit less intense. I have served it in the past with braised oxtails.
sunshine842 pretty much covered the celery root basics, but there's also celery root chips;(like potato chips) thinly slice wedges on a mandolin, deep fry and season with salt and a little ground cumin; celery root makes a great coleslaw on it's own or with other coleslaw vegetables, and of course there's the classic French celery root remoulade; I've linked Julia Child's and David Lebovitz' (with nice photos) recipes here; there's many other variations on this theme on the web:
The epicurious link takes it steps further with some other offerings, particularly the celery root-apple soup and the celery root pommes Anna, which are both delicious:
Celery root is a great vegetable, enjoy!
Treat it like potato -- cubed and roasted, or steamed/boiled and mashed (just heads-up you won't need much liquid) -- simmered into a soup
It's a really delicious vegetable, well worth enjoying. It tastes like celery, but has the texture of a root vegetable.
It's also really good for you - lots of vitamin C, and very low in calories.
down there at the bottom of the page, there are links to:
Celery Root Puree: http://www.chow.com/recipes/28906-celery-root-puree (I've also made it with JUST celeriac...but it's better with potato, as it has a better body and a little more subtle flavor)
and Celery Root Soup: http://www.chow.com/recipes/28907-celery-root-soup
and Celery Root and Mushroom stuffing: http://www.chow.com/recipes/28904-cel...