In a medium saucepan, combine potatoes, 3 tablespoons salt, and water to cover by 1 inch. Bring to a boil over medium-high heat. Cook until potatoes are fork tender, 15 to 20 minutes. Drain potatoes and place in an ice water bath to stop cooking process; drain well. Cut potatoes into quarters.

In a large bowl, combine celery, mayonnaise, mustard, lemon zest and juice, dill, chives, and pepper. Add potatoes and gently stir to combine. Cover and refrigerate for at least 30 minutes. Garnish with dill and pepper, if desired.