I recently roasted five pounds of beets and have been using them for side dishes. I decided to make soup last night, and it turned out quite nice. You may get more servings, but we really like our soup and 4 servings is all I got. I am sure that canned beets would also work quite well. I like evaporated milk because it brings richness with fewer calories, but half-and-half would also be good. I don't usually have fresh celery, but 1/2 cup of chopped celery could be used instead of the flakes and 1/4 tsp fresh ground pepper instead of the peppercorns. Add an hour to the cooking time if you need to roast fresh beets.