Heat the oil in a large saucepan over medium high heat. Add the onions, celery, carrots, leeks, and garlic, and saut
2
Add the tomatoes, lentils, vegetable broth, and bay leaf, and bring to a boil. Then lower the heat and simmer, partially covered, for about 1 hour, or until the lentils are tender. Add the salt and pepper, and remove the bay leaf.