Pour lentils in a bowl, cover with water, and allow to sit overnight.
Over medium heat, cook onions in olive oil in a large soup pan. Add garlic and celery. Once celery begins to soften, add carrots, tomatoes, bay leaf and vegetable stock.
Pour in drained lentils.
Bring to a boil, reduce heat, and allow the soup to simmer for 30 minutes.
Remove and discard bay leaf and add vinegar. Season with salt and pepper to taste.
salt and pepper to taste
Makes 4 servings.
Minutes to Cook: 30
Number of Servings: 1