Double the recipe--as we did here--for a dramatic presentation that will feed a large group.
Wash olives, and drain. Gently pound each olive with a wooden mallet to open. (Don't mash, and don't remove pit.) Place olives and celery in a large bowl.
Whisk together olive oil and next 5 ingredients until blended; pour over olive mixture, tossing to coat. Cover and chill 8 hours. Refrigerate up to 1 month. Serve at room temperature.