Place potatoes in a large pot. Cover with water and bring to a boil. Boil until potatoes are tender, about 20 to 25 minutes. Drain and let potatoes cool a bit.
In a small bowl, whisk together mayonnaise, sugar, and yellow mustard.
In a large bowl, combine potatoes, celery, onion, pickles, and pepper. Add in mayonnaise mixture and gently fold to combine. Season with salt and pepper to taste.
Tips:
Although this salad can be served fresh and warm, it can also be made up to a day ahead. Serve cold or bring to room temperature.