This is an healthy recipe from Healthy Heart Cookbook from the American Medical Association. It's very good and thick. In the directions, it says : the soup should be slightly thickened like a stew. So that's ok if it's thick. Lentils are loaded with protein and fiber, can be kept on hand in the pantry, and cook quickly without presoaking, making lentil soup an excellent anytime meal. Peppery watercress perks up the flavor and adds vibrant color to this earthy soup.