Heat oil in a heavy soup pot. Sauté onions for 5 to 7 minutes, or until translucent. Add all remaining ingredients. Cover and bring to a boil. Reduce the heat to medium-low and simmer for 45 minutes to 1 hour. Adjust the seasoning if needed and cook another 10 minutes. If you desire more heat, a few drops of hot sauce can be added before serving.
Per serving - 200 calories, 5 g fat (23% calories from fat), 9 g protein, 32 g carbohydrate, 9 g fiber, 0 mg cholesterol, 426 mg sodium