How to Make It
In a large saucepan, cover the beans with 3 quarts of cold water. Wrap the quartered onion, parsley stems, smashed garlic cloves, bay leaves and peppercorns in a large square of cheesecloth and tie with kitchen string; add to the beans.
Bring the beans to a boil over high heat, then reduce the heat to moderately low and simmer until almost tender, about 30 minutes. Season with salt and cook until tender, about 10 minutes longer. Drain the beans and let cool slightly.
In a large bowl, whisk the olive oil with the lemon juice. Add the red onion, celery, minced garlic, chopped parsley and beans. Season with pepper and toss gently. Cover with plastic wrap and let stand at room temperature for 3 hours.
Meanwhile, in a large saucepan, combine the beets with the vinegar and 1 tablespoon of salt. Add enough water to reach 3 inches above the beets; bring to a simmer. Cook until tender, about 30 minutes. Cool the beets in their cooking liquid. Drain the beets, then peel and quarter them.
Transfer the beets and beans to plates; serve with the Skordalia and warm pita.