Heat oil in saucepan over medium-high heat. Add shallots, and sauté 2 minutes, or until shallots begin to soften. Add wine, garlic, and cayenne. Simmer 4 minutes.Add carrots, potato, and turnips, and sauté 1 minute. Add broth and 5 cups water. Tie together parsley sprigs, thyme sprigs, and bay leaves with kitchen twine, and add to soup. Season with salt and pepper, if desired. Cover, and bring to a boil. Reduce heat to medium-low, and simmer 20 minutes.Stir in peas, snow peas, and spinach. Cover, and simmer 5 minutes more. Remove herb bundle, and discard. Season with salt and pepper, if desired. Ladle soup into bowls, sprinkle with tarragon, drizzle with olive oil, and serve.