Rinse the lentils in a strainer, with cold running water. Combine the lentils, water, oil and salt in a medium saucepan. Bring to a boil and cook uncovered for 20 minutes over medium heat. Stir occasionally. Add the diced potatoes, spices and stir. Add the onion and garlic and other spices. Cook until the onions begin to tender. Add the onions, garlic and spices to the soup and cook until the potatoes are tender. This will take 20 minutes. Serve hot.