Not sure really, as some have said, a lot of the time it's the whole combination of food/location/service/companions/time&space that create a really memorable dining experience.
Also there's what each person considers "best", which is subjective at best (ref
@Taipan 
....)
Some distinctively memorable meals for me include:
A steak and stone "cook it your way" meal in Belgium last year, the steak cut was perfect (no gristle), and cooking each slice on the marble stone meant that each slice was exactly the way I wanted it, quite possibly the best steak meal I've ever had. (oh yeah - belgian chips.... hraaahgagahahaghag) Experience was enhanced by the banter with my brothers, the warm weather and the fact that we'd spent all day riding bikes on great roads.
Last week in Santiago, Chile, I had sea urchin, "Erezos" tongue. Never had it before, and its supposedly one of those foods that most people can't stand: the flavour is odd to say the least, the texture is weird, but the experience was great, and I've become a far less fussy eater as I've got older, so I actually rather liked the flavour/texture. I'd certainly have it again, but genuinely believe I'll never have it "done" as well as that. Highly recommended if you're in the city:
https://www.tripadvisor.com/Restaurant_ ... egion.html
Fish and chips with added cold seafood fresh caught on the beach at Selsey with friends.
Breakfasts at "Sea View" Douglas each morning on Manx week... memorable, but mainly for the banter, definitely not the food...
