Peel and chop the onion, carrots and parsnips.
Melt the butter in a pan and cook the onion until soft. Add the carrot and parsnip pieces and sauté under cover, at a low temperature for about 15 minutes (stirring occasionally).
When the vegetables have softened, add the ginger, orange peel and vegetable stock. Bring to the boil and simmer gently, under cover, for 25 minutes.
Remove from the heat and rest for 10 minutes. Then add the cream and using a liquidiser or blender whizz until smooth and silky. Season with salt and pepper to taste, then gently heat it up - but don’t let it boil!