This quick and easy soup is a perfect prelude to a meal of barbecued chicken or ribs.
1. In the container of a blender or processor, combine the chicken broth and onion and whirl until smooth. Ad the avocados, lime juice,cilantro, chili powder, salt, and cayenne. Process briefly to incorporate, but do not over-liquefy.
2. Transfer to a large bowl. Blend in the yogurt and cover. Refrigerate until thoroughly chilled. Serve cold, sprinkled with freshly chopped chives.