Preparation Melt butter in heavy medium saucepan over medium-low heat. Add onion and sauté until tender, about 8 minutes. Add flour and stir 2 minutes. Gradually mix in broth. Add peas and chopped tarragon. Simmer until peas are very tender, about 15 minutes. Drain peas, reserving broth. Puree peas in processor. Add 1/2 cup broth and puree until smooth. Gradually blend in remaining broth. Transfer to medium bowl and refrigerate until well chilled. (Can be made 1 day ahead.) Season soup to taste with salt and pepper. Ladle into bowls. Garnish each with small amount of crème fraîche and tarragon leaves and serve.
Preparation Melt butter in heavy medium saucepan over medium-low heat. Add onion and sauté until tender, about 8 minutes. Add flour and stir 2 minutes. Gradually mix in broth. Add peas and chopped tarragon. Simmer until peas are very tender, about 15 minutes. Drain peas, reserving broth. Puree peas in processor. Add 1/2 cup broth and puree until smooth. Gradually blend in remaining broth. Transfer to medium bowl and refrigerate until well chilled. (Can be made 1 day ahead.) Season soup to taste with salt and pepper. Ladle into bowls. Garnish each with small amount of crème fraîche and tarragon leaves and serve.