Simple Carrot and Ginger Soup

This recipe is a very simple carrot and ginger soup from the great vegetarian cook Kurma Dasa.  It has a fresh, cleansing taste, and I love to make it if I feel a cold coming on.
Yellow acefoetida powder is available from asian grocers - it's a great, simple substitute for onions and garlic in many dishes - but very much has its own flavour.  Fantastic in dahl.

Ingredients:
2 tabsp. butter
1/2 teasp. yellow asafoetida powder
2 teaspoons grated fresh ginger
700g topped, scraped and sliced carrots, about 4 1/2 cups
1 cup potatoes, diced
1 1/2 teaspoons salt
1/2 teaspoon black pepper
at least 4 cups light vegetable stock or water
chopped continental parsley leaves for garnish

1. Melt the butter in a 3 litre saucepan over moderate heat.  Sprinkle in the yellow acefoetida power and ginger, stirring briefly.  Add the sliced carrots, potatoes, salt and pepper and sauté for 10 minutes, stirring occasionally. Add the stock or water, and bring to the boil, then reduce the heat and simmer the vegetables, covered, for 15 minutes, or until the vegetables are very tender
2. Remove the pan from the heat, transfer the contents to a blender or food processor and process to a smooth puree
3. Rinse the saucepan, return the soup to the pan, and gently reheat over moderate heat.  For a thinner soup, add extra stock at this stage.  Serve the soup hot with a sprinkle of freshly chopped continental parsley leaves.