Heat oil in a medium saucepan over medium-high heat. Add onion; sauté 10 minutes. Add garlic, and sauté 1 minute. Add tomato, and cook 5 minutes, stirring frequently. Add potato, bell peppers, salt, black pepper, and broth; bring to a boil. Cover, reduce heat, and simmer 20 minutes or until potato is tender, stirring occasionally. Remove from heat; stir in basil and olives. Let stand, covered, 20 minutes.