The plot was something like, family own a cafe and start making their own burgers with a special herb/seasoning blend they found (possibly left by a relative, that owned the cafe before? Not sure about this) and it's like magic and they're the best burgers. Great success. They try and recreate the magic seasoning and I can't remember how they got on with that bit. Does it ring any bells with anyone? I would probably have read it in the late 80s/early 90s.