Simmer potatoes until tender; drain and cool. Cut in half widthwise.
In large bowl, whisk together vinegar, mustard and lemon zest. Slowly whisk in oil; season with salt and pepper. Fold in potatoes and remaining ingredients, except celery curls; adjust seasoning. Marinate for a few hours. Mound in bowl or on individual salad plates; garnish with celery curls.
Note: To make celery curls, with vegetable peeler, shave celery into long strips. Place in ice water for several hours or until strips curl.
For a complete meal: Stir 2 cups coarsely shredded rotisserie chicken, or 3 coarsely chopped hard-cooked eggs, into salad.