Fill a large stockpot with cold water and add the cubed Yukon Gold potatoes along with 1 tablespoon of salt. Bring to a rolling boil, reduce heat and simmer until fork-tender, about 12-16 minutes. Drain and cool.

Preheat your oven to 400°F (200°C). Toss the cooled potatoes with olive oil, garlic powder, salt, and black pepper until fully coated.

Spread the seasoned potatoes on a foil-lined baking sheet. Roast for about 30 minutes, flipping halfway through, until golden brown and crispy.

In a large bowl, combine sour cream and mayonnaise. Add scallions, dill, parsley, Dijon mustard, and lemon juice. Mix well and season with salt and pepper.

Toss roasted potatoes with the creamy dressing just before serving. Garnish with reserved herbs for freshness.