Process cucumber, garlic, and 1 cup broth in a blender or food processor until smooth, stopping to scrape down sides. Pour into a bowl; stir in remaining 1 cup broth, sour cream, and next 4 ingredients. Cover and chill at least 2 hours. Sprinkle with desired toppings.
*1 (16-ounce) container light sour cream may be substituted.