Sweet Potato Soup with Lobster and Orange Crème Fraîche

Preparation Mix cream, sour cream, 1 1/2 teaspoons ginger and orange peel in medium bowl to blend. Let stand until thickened, about 3 hours. Cover crème fraîche and refrigerate. Preheat oven to 400°F. Melt 4 tablespoons butter in large pot over medium heat. Remove from heat. Add sweet potatoes and sugar and toss to coat. Arrange sweet potatoes on 2 baking sheets. Roast until very tender and starting to brown, stirring occasionally, about 30 minutes. Melt 4 tablespoons butter in same pot over medium heat. Add leeks, celery and remaining 1 1/2 teaspoons ginger and sauté until leeks begin to soften, about 5 minutes. Add roasted sweet potatoes and sauté 2 minutes. Add 10 cups broth and orange juice. Bring mixture to boil. Reduce heat and simmer until leeks and celery are very tender, about 20 minutes. Working in batches, puree soup in processor. Return soup to pot. Thin with more broth, if desired. Season with salt and pepper. (Crème fraîche and soup can be made 2 days ahead. Cover separately; chill.) Remove lobster meat from shells. Slice into 1/3-inch-thick medallions. Melt 2 tablespoons butter in heavy large skillet over medium heat. Add lobster; sauté until heated through, about 1 minute. Bring soup to simmer. Ladle into bowls. Spoon small dollops of crème fraîche atop soup. Draw skewer through crème fraîche to form design. Arrange lobster atop soup. Sprinkle with parsley.

Preparation Mix cream, sour cream, 1 1/2 teaspoons ginger and orange peel in medium bowl to blend. Let stand until thickened, about 3 hours. Cover crème fraîche and refrigerate. Preheat oven to 400°F. Melt 4 tablespoons butter in large pot over medium heat. Remove from heat. Add sweet potatoes and sugar and toss to coat. Arrange sweet potatoes on 2 baking sheets. Roast until very tender and starting to brown, stirring occasionally, about 30 minutes. Melt 4 tablespoons butter in same pot over medium heat. Add leeks, celery and remaining 1 1/2 teaspoons ginger and sauté until leeks begin to soften, about 5 minutes. Add roasted sweet potatoes and sauté 2 minutes. Add 10 cups broth and orange juice. Bring mixture to boil. Reduce heat and simmer until leeks and celery are very tender, about 20 minutes. Working in batches, puree soup in processor. Return soup to pot. Thin with more broth, if desired. Season with salt and pepper. (Crème fraîche and soup can be made 2 days ahead. Cover separately; chill.) Remove lobster meat from shells. Slice into 1/3-inch-thick medallions. Melt 2 tablespoons butter in heavy large skillet over medium heat. Add lobster; sauté until heated through, about 1 minute. Bring soup to simmer. Ladle into bowls. Spoon small dollops of crème fraîche atop soup. Draw skewer through crème fraîche to form design. Arrange lobster atop soup. Sprinkle with parsley.