How to Make It
Preheat oven to 400°. Combine potatoes, olive oil, and 1/4 teaspoon kosher salt on a jelly-roll pan; toss. Bake at 400° for 40 minutes, stirring halfway through; cool. Combine green onions, sour cream, mayonnaise, Dijon mustard, pepper, 1/4 teaspoon kosher salt, and garlic powder in a bowl. Add potatoes; toss to coat.