How to Make It
To prepare skordalia, combine first 4 ingredients in a food processor; process until finely grainy. Add mashed potatoes, parsley, and bread; pulse 10 times. With processor on, gradually add 1/4 cup oil until mixture is thick and creamy. Add pepper.
Place garlic mixture in a small bowl; cover with plastic wrap, and refrigerate at least 2 hours. Stir in yogurt, rind, and sumac, if desired, just before serving.
To prepare vegetables, place beets in a medium saucepan; add water to cover, 3 tablespoons juice, and cinnamon, if desired. Bring to a boil; reduce heat, and simmer 30 minutes or until tender. Drain well; cool. Rub peels off beets; discard peels. Cut beets into quarters.
Place red potatoes in a medium saucepan; cover with water. Bring to a simmer over medium-high heat; cook 15 minutes or until tender. Drain well.
Heat a large skillet over medium heat. Add 1 tablespoon oil; swirl to coat. Add snow peas; cook 2 minutes or until crisp-tender, stirring occasionally. Place beets, potatoes, and snow peas on a large platter; sprinkle evenly with 1/2 teaspoon salt. Add lemons to platter. Serve with skordalia.