Peel the potatoes and slice each one lengthwise in half, or in quarters if very large, then cut crosswise into half-round or quarter-round slices, about 1/2-inch thick. Place the slices in a large saucepan with enough water to just cover.  Generously salt the water and heat to a simmer. Cook the potatoes for 6-8 minutes, or until just cooked through. It is important that the potatoes are not over cooked.  Immediately drain the potatoes and transfer to a large bowl. Stir the cider vinegar with the chicken broth and drizzle over the potatoes, gently turning them to distribute the mixture.  Gently transfer the potatoes to a baking sheet in one layer and let them rest for 10 minutes to absorb the liquid.

Return the potatoes to the bowl and add the celery, bacon, gherkins, eggs, mustard, scallions, and parsley.  Begin by adding just 1/2 cup of the mayonnaise and, using a large rubber spatula, gently fold everything together until well blended.  Season with salt and pepper to taste, adding more of the mayonnaise if needed.

Cover the salad and refrigerate for an hour before serving.  If it is refrigerated longer, allow it to come to room temperature before serving.  Enjoy!