1. In a large pot, add the potatoes and enough water to cover. Add salt and bring the water to a boil. Cook the potatoes for 10 to 15 minutes or until tender when pierced with a fork. Drain and set aside to cool slightly.
2. In large bowl, combine potatoes, celery, onions, parsley, salt and pepper. In small bowl, stir mustard together with the dressing until well blended. Pour over potato mixture and toss until lightly coated. Chill covered for at least 1 hour, overnight is best.
3. Serve in a bowl lined with lettuce leaves (optional) and garnish with the chopped egg and paprika.