Citrus Fennel Shrimp with Tarragon

4 cups water

1 cup dry white wine

1 lemon -- sliced

1 lime -- sliced

1 tablespoon salt

1 bay leaf

1 onion -- quartered

1 pound medium shrimp (about 32) -- deveined and

-- shelled, leaving -- tail intact

2 tablespoons fresh lemon juice 2 tablespoons fresh lime juice 2 teaspoons fennel seeds, crushed Pinch dried hot red pepper flakes 6 tablespoons olive oil 3 large garlic cloves, crushed 2 teaspoons finely chopped fresh tarragon leaves Garnish: Tarragon sprigs

In a large pot, bring water and wine to a boil with 1/2 of the lemon and lime slices, salt, bay leaf and onion and boil 5 minutes. Add shrimp and cook, stirring occasionally, until just cooked through, about 3 minutes. Drain shrimp and cool.

In a bowl whisk together lemon juice, lime juice, fennel seeds, red pepper flakes, and salt and pepper to taste and add oil in a stream, whisking. Stir in shrimp, garlic, reserved lemon and lime slices and marinate, covered and chilled, stirring occasionally, at least 6 hours or overnight. Stir in chopped tarragon. Serve shrimp garnished with tarragon sprigs.