I do not quite understand. Are you interested in just gourmet food or just distinctive for Russian cuisine?
If it’s delicious, it is usually black caviar, Kamchatka crab, meat products from wild animals (deer, wild boars, roe deer, moose, bears).
If the question is about distinctive dishes, then it's easier to give a link to the wiki: https://ru.wikipedia.org/wiki/%D0%A0%D1%83%D1%8...
(I recommend reading the article in Russian, it is more accurate than the English version of the article).