Yeah, it's bugging me too how a tribe with a rather developed culture has made zero headway in the culinary arts that the word "delicious" isn't even part of their vocabulary.
But it isn't really anything new. A bunch of other isekais have the protagonist make modern cuisine, especially of the Japanese sort, which is treated like ambrosia by the isekai world's denizens, and instantly above and beyond any food they can make.
I can only wish they were less masturbatory. Making the other side very interested in unique cuisine they've never encountered before is interesting and a natural reaction, but much less so when the characters that introduces it to them, along with the food as well, start being treated as divine.
It would be perfectly fine if the elves were amazed by the protagonist's cuisine by sheer virtue of how different it is. Hell, they could also be interested by some of his modern techniques in cooking and preparing meals. But to make them have zero culinary knowledge and ability is just taking it too far.