Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large bowl, toss potato cubes with olive oil, salt, and pepper until evenly coated.
Spread potatoes in a single layer on prepared baking sheet. Roast for 30-35 minutes, stirring halfway through, until golden brown and crispy.
While potatoes roast, whisk together mayonnaise, sour cream, Dijon mustard, dill, parsley, red onion, and apple cider vinegar in a medium bowl.
Let roasted potatoes cool for 5-10 minutes until warm but not hot.
Gently fold warm potatoes into dressing mixture until evenly coated.
Let salad rest for 10 minutes before serving to allow flavors to meld.