Celery Root Soup with Shaved White Truffles

I've been on a tuberous jag lately. It seems that each winter I adopt a different root vegetable for extra attention in the kitchen. Parsnips, beets, turnips, burdock, and yams have all had their due, among others, and let's not forget those tuber-like fungi, truffles. This year the winner is the homely looking celery root. Seems I'm not alone. Celery root, or celeriac, is more prevalent on