Heat the olive oil in a large soup pot over medium heat. Add the chopped onion and cook, stirring occasionally, for about 5 minutes, until translucent. Add the garlic and continue cooking for 1 to 2 minutes, until both are golden and fragrant.

Stir in the lentils, pearl barley, celery, carrots, cabbage, diced tomatoes (with their juices), red wine (if using), cider vinegar, parsley, salt-free seasoning blend, and paprika. Add the 6 cups of water and bring to a gentle boil over medium-high heat.

Reduce the heat to low, cover, and simmer for 45 to 55 minutes, stirring occasionally, until the lentils, barley, and vegetables are tender. Add more water as needed if the soup becomes too thick.

Season with salt and pepper to taste, and stir in extra fresh parsley or dill if desired. For the best flavor, let the soup stand off the heat for about an hour, then reheat gently before serving. The soup thickens as it stands, so add water and adjust the seasonings just before serving.