Peel and dice the onions and fry them in olive oil until translucent, clean the soup vegetables, cut them into small pieces and add them to the onions.
Stir the tomato paste into the vegetables, pour the vegetable stock and bring to the boil.
Stir in the lentils, season everything with salt, pepper and bay leaves and simmer for about 10 minutes.
Chop the tomatoes, add them to the lentil soup, and simmer for another 15-20 minutes.
Serve the lentil soup with warm baguette bread or ciabatta.