1 pound fresh celery root (celeriac) (peeled and diced, 1/4-inch)
1 pound Earthbound Farm Organic Yellow Potatoes (peeled and diced,1/4-inch)
2 teaspoons coarse (kosher) salt
6 cups water
1/2 cup chicken stock or heavy (whipping) cream
2 tablespoons butter
  freshly ground pepper (to taste)