Cut off the greens of the beet and wash it gently, trying not to break the skin. Place the washed beet in a pot. Pour water until beet is covered. Optional: at this point you can add 1-tablespoon sugar, if you like the sweet taste. Cover the pot and bring to a boil. Simmer for 45 minutes (depending on size) or until beet can easily be pierced through with a fork. As soon as it is cool enough to handle, gently rub the beet to remove the outer layer of skin and then grate the beet.
In a bowl, mix the grated beet, yogurt and garlic. Season with salt. Cover and chill at least 3 hours.