01 - Place potatoes in a large pot and cover with cold salted water. Bring to a boil, reduce heat, and simmer for 12–15 minutes, until just fork-tender. Drain and let cool slightly.
02 - While potatoes are cooking, cook bacon in a skillet over medium heat until crisp. Remove, drain on paper towels, and crumble.
03 - In a small bowl, whisk together mayonnaise, sour cream, Dijon mustard, apple cider vinegar, sugar, salt, and pepper to make the dressing.
04 - In a large mixing bowl, combine the warm potatoes, celery, red onion, scallions, and half of the bacon. Pour the dressing over and gently toss to coat evenly.
05 - Transfer to a serving bowl. Top with remaining bacon, chives, and a sprinkle of paprika if desired. Chill for at least 1 hour before serving for best flavor.