Puréed Celeriac and Potato Soup

If you’re one of those cooks who always use stock for soup, try water first this time: the frank celeriac and potato flavors are dandy in the foreground, instead of hidden.

If you like, serve this thick, homey family soup with a garnish—minced fresh herbs, croutons (whole-wheat are nice) sautéed in butter, snippets of ham or sausage, or whatever is on hand. The pleasing pottage is quickly assembled and, unlike most such purées, does not require mellowing time—although holding it doe