Image credit to: Boston Organics
Roast the beets in a covered baking dish filled with 1/4 inch of water at 425 F for 30-40 minutes. Remove from oven when beets are easily penetrated with the tip of a knife. Allow to cool, cut off ends and slip off the skins. Finally, cut into wedges or slice into half-moons.
Meanwhile, stir together the vinegar, sugar, olive oil, and salt and pepper to taste. Toss with the warm beets and allow to marinate for 2 to 3 hours at room temperature or in the refrigerator.
Place the garlic in a mortar and pestle, add 1/8 teaspoon salt, and mash to a paste. Stir into the Greek yogurt. Stir in half the dill. Add salt and pepper to taste. Drain the beets and stir some of the marinade into the yogurt (to taste). Toss with the beets, or arrange the beets on a platter and drizzle the yogurt over the top. Sprinkle on the remaining dill, and serve.
Note: If you mix the yogurt into the beets, your salad will turn pink. This can be a desired effect, but if you prefer you can also spoon the yogurt over the top.