Heat the oil in a dutch oven or large saucepan over medium-high heat. Add the onion and sauté 3 minutes or until tender.

Add broth and next 6 ingredients. Bring to a boil, reduce heat and simmer uncovered 20 minutes or until the beets and potato are tender. Be sure to discard bay leaf at this point.

Puree mixture using an immersion blender. You may also use a blender or food processor, being sure to process in 3 batches. The blender will probably give the smoothest results, but I thought the immersion blender gave satisfactory results (plus was easy to use). Return pureed mixture to the pot if necessary. Warm soup over low heat 5 minutes. Remove and stir in lemon juice.

Remove 1/2 cup of the soup and transfer this into a small bowl. Combine it with the sour cream, stirring with a whisk.

Ladle the soup into individual bowls and top each serving with one tablespoon of the sour cream mixture. Using the tip of a knife, swirl the sour cream, making a pretty design.

This recipe makes 8 servings (3/4 cup each) at 74 calories.