Janie, I've never tried a mustard dressing. Maybe you could adapt a niçoise dressing recipe. I'm really happy with the mayo + sesame oil. I made it for a summer party, and wondered "what if". I came home with leftovers an added more of the oil. It's easy enough to take a little bit of the coleslaw and add something to it, just for a taste, although that precludes using a completely new dressing.