Boil the Yukon gold potatoes in salted water until fork-tender, about 12 to 16 minutes. Drain and cool slightly.

Preheat oven to 400°F. Line a baking sheet with aluminum foil.

Toss potatoes with olive oil, garlic powder, salt, and pepper. Spread on the baking sheet.

Roast potatoes for about 30 minutes, flipping halfway through for even browning.

In a bowl, combine sour cream, mayonnaise, scallions, dill, parsley, mustard, and lemon juice. Mix well.

Gently fold the crispy potatoes into the dressing mixture once cooled slightly.

Transfer the salad to a serving dish and garnish with reserved herbs.