1. Combine first 6 ingredients in a large saucepan; bring to a boil. Reduce heat; simmer 2 minutes or until carrots are tender.
2. Place half of soup mixture in a blender or food processor. Remove center piece of blender lid (to allow steam to escape); secure blender lid on blender. Place a clean towel over opening in blender lid (to avoid splatters). Blend 30 seconds or until smooth. Pour pureed mixture into a large bowl. Repeat procedure with remaining soup mixture. Ladle soup into bowls; garnish with yogurt and thyme sprigs, if desired.