Place all ingredients, except for crème fraiche and dill, into a high speed juicer. Purée until smooth. Pour into a nonreactive bowl and season with salt and pepper to taste. Place in refrigerator to cool for at least !/2 hour.
To serve:
Ladle soup into 8 bowls and add the crème fraiche in even dollops across the 8 bowls. Garnish with fresh dill sprigs. Serve immediately.