• Step 1: Place the cubed potatoes in a large pot and cover with cold water. Bring to a boil over high heat, then reduce the heat to medium-low and simmer for 10-12 minutes, or until the potatoes are fork-tender. Drain the potatoes and let them cool to room temperature.
• Step 2: In a large mixing bowl, whisk together the mayonnaise, sour cream, Dijon mustard, white vinegar, sugar, salt, and black pepper until well combined.
• Step 3: Add the cooled potatoes, diced celery, diced red onion, and chopped hard-boiled eggs to the dressing. Gently fold everything together until the potatoes are evenly coated.
• Step 4: Garnish the potato salad with chopped fresh parsley, if desired. Refrigerate for at least 2 hours before serving to allow the flavors to meld.