How to Make It
Fill a large saucepan with 1 inch of water and fit with a steamer basket. Steam the potatoes until tender, 15 to 18 minutes; let cool.
Toss the potatoes with the sour cream, mayonnaise, dill, lemon juice, scallions, 1 teaspoon salt, and ½ teaspoon pepper. Refrigerate for up to 8 hours.