Cousin Walter and those who dined with him looked forward to this well-chilled light beet soup on warm days. Milk, plain yogurt, or a combination of the two can be used instead of buttermilk. ~------------------------------------------------------------------------Melt the butter in a medium saucepan. Add the onions and celery, and saute over medium heat for 10 minutes, or until the celery is soft and golden. Add the celery leaves and cook for 2 minutes longer. Add the remaining ingredients except the buttermilk and dill. Bring to a boil, lower the heat and simmer for 20 minutes, or until the beets are tender. Cool. Stir in the buttermilk and dill. Chill thoroughly.