Heat oil in a large pot over medium heat. Add onion, carrots, celery, and garlic. Cook, stirring occasionally, until vegetables are softened, about 5 minutes.
Add oregano, basil, thyme, bay leaf, and broth. Bring to a boil. Reduce heat to low, cover, and simmer for 10 minutes.
Stir in lentils, tomatoes, and season with salt and pepper. Cover and simmer until lentils are tender, about 15 minutes.
Remove bay leaf and discard. Serve hot.
Interesting Facts
Lentils are a great source of fiber, protein, and iron.
This soup is a great make-ahead meal. Just store in an airtight container in the refrigerator for up to 3 days.
This soup can also be frozen. To freeze, let cool completely and then place in an airtight container and freeze for up to 3 months.