Saute leeks, onion, carrots and celery in olive oil until slightly soft, about 3-5 minutes. Add lentils, barley, spices and vegetable stock. Bring to a boil, then lower heat and simmer, covered, about 1 ½ hours. Add more broth or water as needed. Add tomatoes and cook ½ hour longer. Stir in swiss chard and cook until just tender, about 3-4 minutes. Season with salt and pepper.