6 medium beets
1 red onion, thinly sliced
1/2 cucumber, sliced
5 tablespoons plain yogurt
2 tablespoons mayonnaise
1 tablespoon red wine vinegar
1/2 teaspoon prepared Dijon-style mustard
1/2 teaspoon prepared horseradish
2 tablespoons dried dill weed
1/3 teaspoon salt
1/3 teaspoon ground black pepper