1. Process chicken broth, green onions, vinegar, salt, pepper, and half of chopped cucumbers in a food processor until smooth, stopping to scrape down sides.
2. Add yogurt, and pulse until blended. Pour into a large bowl; stir in remaining chopped cucumbers. Cover and chill 4 to 24 hours. Season with salt to taste just before serving. Garnish, if desired.
*Plain low-fat yogurt may be substituted. Decrease chicken broth to 1/2 cup.