Wash potatoes. Heat 1 inch salted water to boiling. Add unpared potatoes. Cover tightly; heat to boiling and cook 30 to 35 minutes or until tender. Drain; cool and peel. Cut potatoes into cubes; combine in bowl with onion. Sprinkle with salt and pepper. Mix with Italian salad dressing. Cover; refrigerate at least 2 hours. Just before serving, add mayonnaise; toss until potatoes are well coated. Stir in celery and eggs. Makes 4 to 6 servings.