Jerusalem artichokes are easy to grow; in fact, they can spread vigorously in an untended garden.
Combine artichokes, onion, carrots, and stock in soup kettle, and simmer, partially covered, 10 minutes or until artichokes are soft. Press through food mill. Return to kettle. In separate bowl combine cream and egg yolks. Pour ½ cup hot pureed soup into egg and cream mixture, blend with whisk, and return mixture to kettle. Add sherry, heat, and season with salt and pepper.