Green Pea Soup with Tarragon and Pea Sprouts

• 2 16-ounce packages frozen petite peas, divided (do not thaw)
• 2 tablespoons extra-virgin olive oil
• 1 1/2 cups sliced shallots (about 11 ounces)
• 4 cups (or more) vegetable broth
• 3 tablespoons chopped fresh tarragon, divided
• Plain nonfat yogurt, stirred
• Small fresh pea sprouts*

Place 1 cup peas in microwave-safe bowl; set aside. Heat oil in heavy large saucepan over medium-high heat. Add shallots and sauté until golden and almost tender, about 7 minutes. Add remaining peas, 4 cups broth, and 2 tablespoons tarragon; bring to boil. Reduce heat to medium and boil until flavors blend and peas are tender, about 7 minutes. Cool slightly. Working in batches, puree soup in blender until completely smooth. Return soup to same saucepan. Bring to simmer and thin with more broth by 1/4 cupfuls, if desired. Stir in remaining 1 tablespoon tarragon. Season with pepper.

Cook reserved 1 cup peas in microwave until warm, about 1 minute.

Ladle soup into 6 bowls. Drizzle lightly with yogurt. Sprinkle whole peas over and garnish with pea sprouts.