Truffled Creamy Potato Soup

Potatoes, leeks, and celeriac are a backdrop to the foreground aroma of fresh black truffle—which is pounded to a paste, sluiced with cream, then stirred into the soup to disperse its scent. The more flavorful the truffle and the more of it, the more vivid the soup—but it is a quiet one, nevertheless, for subtle palates. For a sweeter variation, substitute well-scrubbed sunchokes for the celeriac and add one tender celery stalk.