Heat oil in a large Dutch oven over medium heat. Add onion; sauté 3 minutes. Add garlic; sauté 1 minute. Add water and next 6 ingredients (water through broth). Bring to a boil, reduce heat, and simmer 20 minutes. Add spinach and beans; cook 3 minutes. Stir in pepper sauce. Sprinkle with cheese. Serve with lemon wedges, and garnish with fresh oregano sprigs, if desired.