Bring Broth, Pepper, Bay Leaves And Ham To A Simmer. Cook For 30 Minutes. Saute In Butter, The Celery, Onion, Carrot And Leek For 5 Minutes. Add This Mixture To The Soup Along With Lentils. Bring To A Simmer For 30 Minutes. Add Potatoes And Simmer For 30 Minutes. Saute Bacon In Small Skillet Until Crisp. Remove Bacon And Add To The Soup. Stir The Flour Into The Bacon Drippings. Saute Until The Flour Darkens About 5 Minutes. Ladle In 1 Cup Broth To The Flour And Mix Well. Pour The Flour Mixture Into The Soup. Simmer For 10 Minutes. Remove Bay Leaves And Serve.