01 - Place potatoes in a large pot, add enough cold water to cover, and stir in 1 tablespoon salt. Bring to a boil, then simmer for 10 to 12 minutes until fork-tender. Drain in a colander and let cool slightly.
02 - While potatoes are cooking, fry chopped beef bacon in a large skillet over medium heat until evenly crispy. Transfer to a paper towel-lined plate and set aside.
03 - In a large mixing bowl, whisk together sour cream, mayonnaise, Dijon mustard, and black pepper until smooth.
04 - Add warm, drained potatoes to the mixing bowl with the dressing. Use a spatula to gently fold potatoes into the mixture until evenly coated.
05 - Fold in celery, most of the green onions (reserve some for garnish), shredded cheddar cheese, chopped parsley, and most of the cooked beef bacon, mixing gently until incorporated.
06 - Taste and season with additional salt and black pepper as needed.
07 - Transfer to a large serving bowl or platter. Garnish with reserved green onions, remaining beef bacon, and extra parsley. Serve warm, at room temperature, or chilled.