1.
BRING a large pot of salted water to a boil; add potatoes. Simmer 20 to 25 minutes or until tender. Drain; cool slightly. Cut potatoes in half and then each half in quarters; set aside.
2.
COMBINE mayonnaise, oil, vinegar, mustard, chives, sugar, salt and pepper; whisk until well blended. Gently stir in celery, onion, eggs, parsley and chopped potatoes. Mix well.
3.
REFRIGERATE, covered, several hours or overnight. Taste before serving; add additional salt and pepper to taste. Garnish with sliced hard-cooked eggs and chopped fresh chives if desired.