Leave root and 1 inch of stem on the beets; scrub with a brush. Place beets on a foil-lined baking sheet. Bake at 425º for 45 minutes or until tender; cool. Trim off beet roots, and rub off skins. Coarsely chop beets. Combine beets, onion, and celery in a large bowl.
Combine vinegar and remaining ingredients. Pour over beet mixture; toss gently to coat. Serve at room temperature or chilled.