Spray oil in a large pan on medium high heat and add the vegetables.
Cook, stirring frequently for about 10 minutes until they are soft.
Add tomato paste, lentils and broth. Add pepper or any other seasonings you are using. DO NOT add salt at this time.
Bring to a boil and then reduce heat to a simmer. Cover and cook for 45 - 60 minutes, stirring occassionally.
If the soup becomes too thick add more broth 1/2 cup at a time.