In a large kettle, heat the oil and sweat the vegetables and the smoked sausage, about 10-12 minutes. Add the lentils, seasonings, water, and tomatoes. You may substitute regular tomatoes in this step if you would like a less spicy dish. Bring to a boil, reduce heat to a simmer and cover. Cook for 1½ hours or until the lentils are soft. You may need to add more water. Taste for seasoning and serve hot over rice with hot french bread.