Saute the onion in margarine covered for 5 min, without browning. Then add the carrots & ginger. Cover and cook for a further 10 min. Stir from time to time.
Add the stock or water and bring to a boil, then simmer gently for 15 min, until the carrots are tender. Puree the soup in a food processor, then sieve (not really necessary).
Return the soup to the rinsed out pan, reheat gently and season to taste with pepper.
You may use parsnips instead of carrots and add 1 t. Curry powder to the onions when you saute them. A swirl of yogurt on top is good and add some crisp croutons.