Combine broth, tahini, juice, 1 teaspoon oil, and next 4 ingredients (1 teaspoon oil through chickpeas) in a food processor, and process until smooth, scraping sides.
Place potato in a saucepan, and cover with water. Bring to a boil. Reduce heat; simmer 15 minutes or until tender.
Drain and return potato to pan. Stir in broth mixture, and mash to desired consistency. Cook 2 minutes or until thoroughly heated, stirring constantly. Drizzle potato mixture with 1 tablespoon olive oil, and garnish with lemon wedges, if desired.