Heat oil in a pan and sweat off the onions with the spices and garlic. Remove from pan. Add the potatoes and carrots with the stock. Cover with a lid and bring back to the boil and simmer for 10 minutes. Remove from the pan and reserve. Add the onions and spice mix remaining chicken stock and lentils and bring to a boil. Return to a simmer and cook for 40 minutes. Blend the soup; bring back to a boil and add reserved vegetables bacon and tomato purée. Cook for 10 minutes check seasoning and serve.