A good recipe for middle or end of winter especially if you're faced with an overabundance of  winter root vegetables.  The celeriac makes a really nice mild celery flavoured soup but can, along with the parsnip, be substituted by other vegetables.  Any leftovers can be frozen for a quick nutritious meal further down the track.

6 celeriac (good size)
3 parsnips
1 leek
Large handful of parsley
Chives to taste
Butter

Melt the butter (1 to 2 Tbsp or less if you wish), add finely chopped leek and sautee until soft. Add celeriac and parsnip chopped into cubes and cook for a few minutes.  Add water to cover and simmer until vegetables are soft.  Remove from heat and add chopped parsley and chives then blend until smooth in a food processor.  Return to low heat and add water until the desired consistency is reached.  Add salt and pepper to taste.