Sweat onion and leeks in butter and oil in a large pot until soft, then add sweet potatoes, stirring well. Add all but
Cool soup to room temperature, then purée in blender or food processor and season to taste. Chill in refrigerator for at least 3 hours. If too thick to pour fluidly when cold, thin with a small amount of half-and-half.
About 15 minutes before serving, poach salmon cubes briefly in a small pan in remaining beef stock. Remove gently from liquid and drain on paper towels, blotting carefully to remove white residue.
Divide salmon cubes, smoked salmon, and salmon roe evenly between six chilled, wide, flat soup bowls (not cups), preferably white, arranging them in an attractive pattern. Scatter chives evenly over the six bowls, including rims.
Serve by placing bowls on table without soup, then ladle soup or pour soup from a pitcher into them.
© 1992 Colman Andrews. All rights reserved.