1. Sort and wash chickpeas; place in a bowl. Cover chickpeas with water to 2 inches above chickpeas; cover and let stand 8 hours. Drain.
2. Combine chickpeas and 6 cups water in a large saucepan; bring to a boil. Reduce heat, and simmer 2 hours or until very tender. Drain in a colander over a bowl; reserve 2/3 cup cooking liquid.
3. Place tomatoes in a bowl; cover with boiling water. Cover and let stand 20 minutes or until tender; drain. Set aside 1 tablespoon tomatoes.
4. Combine chickpeas, reserved 2/3 cup cooking liquid, tahini, juice, salt, cumin, pepper, and garlic in a food processor; process until smooth.
5. Stir in tomatoes and 1 tablespoon preserved lemon. Spoon mixture onto a serving plate; spread to a 3/4-inch thickness. Sprinkle with reserved 1 tablespoon tomatoes, remaining 1 tablespoon preserved lemon, and parsley. Drizzle with oil.