In a large soup pot, heat olive oil over medium heat. Add onion and saute until translucent.
Add carrots, celery, mushrooms and garlic, saute for 2-3 minutes stirring occasionally.
Add broth, water, lentils, barley, bay leaf, oregano and bring to a boil. Reduce heat and simmer for 30-45 minutes or until lentils and barely are tender.
In the last few minutes of cooking, add the fresh parsley and season with sea salt and pepper as needed.