- Melt butter in large saucepan over medium heat. Add onions and cook, covered, stirring occasionally, until softened, about 8 minutes. Stir in peas and broth; bring to boil. Reduce heat and simmer until peas are tender, about 5 minutes.
- Remove saucepan from heat; stir in buttermilk, tarragon leaves, salt, and pepper; let cool slightly.
- Puree soup, in batches, in blender or food processor. Return soup to saucepan and reheat over medium-low heat. Ladle evenly into 4 bowls. Top each serving with 3 shrimp and garnish with tarragon sprig and half slice of lemon.
- Per serving: 1 cup soup and 3 shrimp
Pretty as a picture, this elegant soup an also be served chilled. White pepper, less potent and "fruitier" than black pepper, is suggested here so the soup isn't dotted with black specks.