In a saucepan, heat the olive oil. Add the chopped onion and chile peppers and saute for a few minutes.
Add the plum tomatoes and juices from the can. With the back of a wooden spoon, break up the tomatoes into little chunks. Add the lentils, and season with salt and pepper. Add the water and allow to cook for approximately 15 to 20 minutes, until the soup has thickened.