This appetizer showcases the earthy, sweet flavor and vibrant color of roasted beets.
In small bowl, combine yogurt, mint and chives. Cover and refrigerate. Preheat oven to 400°F.
Cut beet greens off beets and set aside. Thoroughly scrub beets; cut off both ends. In large bowl, combine oil, garlic, rosemary, cayenne, salt and pepper. Place beets in bowl and mix to lightly coat. Place beets on baking sheet (reserve marinade) and bake, tossing occasionally, until tender, 45 to 55 minutes.
While beets are roasting, wash and remove stems from greens and chop. In heavy-bottomed sauté pan, heat reserved marinade. Add onion and saute until soft, about 6 minutes. Add greens and cook until greens are thoroughly wilted, about 3 minutes. Remove from heat and season with salt and pepper.
Place bread slices on baking sheet and toast on both sides, about 3 minutes. When beets have cooled (you may peel them if desired), cut in half and thinly slice. Place in medium bowl and add brown sugar and vinegar. Toss and season.
To serve, place a generous amount of beet greens on top of toasted bread. Top with beets and garnish with yogurt-herb dressing and a sprinkle of chives.