1
Adjust rack to top position and preheat oven to 425 degrees. Wash and dry all produce.
Trim and thinly slice scallions, separating whites from greens; finely chop whites until you have 1 TBSP (2 TBSP for 4 servings). Quarter lemon. Cut potatoes into ½-inch-thick wedges.
In a small bowl, combine mayonnaise, mustard, chopped scallion whites, half the sour cream (you’ll use the rest later), half the paprika (you’ll use the rest in the next step), and a squeeze of lemon juice to taste. Season with salt and pepper.