Add the potatoes to a large pot and fill with water to cover at least 2 inches above the potatoes. Season with salt. Bring to a simmer and cook until potatoes are fork tender, about 20-30 minutes. Strain.
Meanwhile, mix the pickle juice, mustard, and yogurt in a large bowl.
Add the still warm potatoes to the yogurt mixture and stir to combine. Season with salt and pepper. Some of the potatoes will break up and mash into the yogurt. Refrigerate for at least an hour to cool.
Add the pickles, celery, scallions, and dill to the potatoes and stir well. Taste and adjust seasonings if needed.