In a large skillet heat oil over medium high heat. Stir in onion and cook for 2 minutes. Stir in garlic, cayenne, cumin, chili powder and cook for 1 minute. Stir in tomatoes, beans, and water and stir well. Simmer mixture for 15-20 minutes or until it has thickened. Stir in the chopped parsley or cilantro. Serve hot over rice with various toppings.