Sweet Potato Bisque with Clementines and Sage

Why I Love This Recipe
This is a nice soup from Vegetarian Times article on clemintines, January 2005.
Ingredients You'll Need
2 tablespoons unsalted butter
3 stalks celery -- chopped
3 fresh sage leaves -- chopped
1 medium yellow onion -- chopped
1 medium parsnip -- peeled and chopped
1 large carrot -- peeled and chopped
4 to 6 Clementines
6 medium sweet potato -- peeled and chopped
3 tablespoons white wine
1/2 teaspoon ground nutmeg
1 teaspoon fresh ginger -- grated
5 cups vegetable broth
3 tablespoons heavy cream
Directions
Heat burner in large pot over medium heat. Add celery, sage, onion, parsnip and carrot, and cook, stirring, until onion has softened and is just beginning to brown, about 5 minutes.
Meanwhile, squeeze Clementines to make 3/4 cup juice; set aside. Grate zest from Clementines, set aside.
Add sweet potatoes, and cook 2 minutes. Add wine and bring to a boil, scraping up brown bits on bottom of pot. Add clementine juice, nutmeg and ginger. Add vegetable stock, reduce heat to low and cook 25 minutes until sweet potatoes are tender.
Working in batches, puree mixture in food processor or blender. Add zest and cream to soup. Heat through, and our into warm bowls.