How to Make It
Stir together lentils, tomatoes, carrots, celery, onion, garlic, oregano, broth and 2 cups water in a slow cooker. Cover and cook on low until lentils and vegetables are tender, about 6 hours. Remove 2 cups; place in a blender. Let cool for about 5 minutes. Puree mixture; return to slow cooker.
Season soup with salt and pepper. Stir in red wine vinegar and serve, sprinkling each bowl with parsley and passing grated Parmesan at the table, if desired.
Also appeared in: All You, April, 2013