Place beans, salt, dried spices, and water in a slow cooker. Cook for 6.5 hours or until the beans are very tender, but not mush. Place beans and 1/2 cup bean broth in a blender or food processor with tahini, lemon juice, and optional ingredients. Process until creamy smooth. Add salt to taste. Serve immediately, refridgerate for up to a week, or freeze for up to four months (if freezing, thaw slowly-DO NOT microwave).