1Heat 1 inch water (salted if desired) to boiling in 3-quart saucepan. Add potatoes. Cover and heat to boiling; reduce heat. Cook 30 to 35 minutes or until tender; drain. Cool slightly; cut into cubes.
2Mix mayonnaise, vinegar, mustard, salt and pepper in large glass or plastic bowl. Add potatoes, celery and onion; toss. Stir in eggs. Cover and refrigerate at least 4 hours until chilled.