1. Peel potatoes if preferred, then cut into halves or thirds. Place in a pot with cold water about 1 inch over the potatoes. Add 1 tablespoon salt and bring to a boil over high heat. Cook for 13 to 20 minutes until fork tender, then drain well. Mash for a fluffy texture.
2. In a large bowl, gently fold mashed potatoes with mayonnaise, mustard, green onions, salt, pepper, and optional paprika. Add vinegar, celery seeds, or dill if using.
3. Fold in chopped pickles or relish, hard-boiled eggs, and bacon if desired. Adjust seasoning with more salt, mustard, mayonnaise, or pickle juice to taste.
4. Chill the salad for at least a few hours or overnight for best flavor. Serve cold and consume within three days, or up to one week with fresh dill and celery.