Lentil Vegetable Soup Recipe

Chop carrots, celery, onion, and garlic. Heat oil in a large soup pot. Add vegetables and bay leaves. Cook on medium heat until vegetables are soft. Add water, herbs, and lentils. Cook on medium-high heat for 45 minutes, adding water when needed (2 or more cups will evaporate during cooking).
Chop potatoes into small cubes, if using. Add to the soup and cook until potatoes are soft, about 10-12 minutes. Add spinach leaves and cook 2 minutes more, just enough to wilt the leaves. Remove from heat. Stir in red wine vinegar and leave covered until ready to serve.

Note: This soup improves with time. Letting it sit for 2 hours will only make it better (if you can wait that long...I usually can't).