In Dutch oven place potatoes. Cover with water. Over high heat, heat to a boil. Cook 20 minutes or until tender. Drain. Cut into cubes.
In medium saucepan gradually mix broth into flour, sugar, celery seed, salt and pepper until smooth. Add vinegar and onion. Over medium heat, cook until mixture boils and thickens, stirring constantly. Reduce heat to low. Cook 5 minutes or until onion is tender.
In large bowl toss potatoes, parsley and broth mixture until evenly coated.
**this can be made ahead and slightly warmed in the microwave.