To prepare the salad, leave root and 1 inch stem on the beets, and scrub with a brush. Place beets in a medium saucepan; cover with water. Bring to a boil; cover, reduce heat, and simmer 35 minutes or until tender. Drain and rinse with cold water. Drain; cool. Trim off beet roots, and rub off skins. Cut into 1/4-inch-thick slices. Set aside.
Cook the green beans in boiling water for 4 minutes or until crisp-tender. Drain and rinse the beans under cold water, and drain well. Combine beans, celeriac, fennel bulb, and chopped chives in a large bowl.
To prepare dressing, combine yogurt and remaining ingredients, and stir well with a whisk. Pour over the green bean mixture, tossing to coat. Divide the beets evenly among 6 salad plates; top each serving with 1 cup green bean mixture.