How to Make It
Melt the butter in a large saucepan. Add the shallots and cook over low heat until softened, about 5 minutes. Add the potatoes, carrots and chicken stock and bring to a boil. Cover and simmer over low heat until the vegetables are tender, about 10 minutes.
Add the parsley, basil, cilantro and tarragon to the soup. Working in batches, puree the soup in a blender. Return the soup to the saucepan, add the lemon juice and season with salt and pepper. Spoon a dollop of crème fraîche into 6 bowls. Ladle the soup on top; serve.