Put all the ingredients except for the vinegar, seasoning and garnish in a large, heavy pan. Bring to a boil over medium heat, then lower the heat and simmer for 1½ hour, stirring the soup occasionally to prevent the lentils from sticking to the bottom.
Remove the bay leaves and add the red wine vinegar, with salt and pepper to taste. If the soup is too thick, thin it with a little extra vegetable stock or water. Serve the soup in heated bowls, garnish with celery leaves. Serve with warmed crusty rolls. From the Ultimate Soup Bible
Recipe by Living Full on Life at https://www.livingfullonlife.com/?p=1799