(Food) Dishes Only Good That One Time/Place

When I was a wee lad, I remember taking a bite of a soft shell crab sandwich (one of my parents must have ordered it - hot dogs only for the kiddies) at Nathan’s Famous, and loving it. Any time I’ve ordered it since at other places, as an entree or a sandwich, and it’s been less than meh. Perhaps I’m misremembering, or maybe it’s because I haven’t been back to either of the Nathan’s - Coney Island (#1) or Oceanside (#2) - that might still serve it, but at this point it is the “meal that got away”.

Any dishes/meals that either haven’t come close to living up to that “one time”, or any place that serves an item that is so far and above the competition that you’ll only order it from there?