https://en.m.wikipedia.org/wiki/Lucien_Olivier

I suppose he was of franco-belgian descent, but he was born in Russia, raised in Russia, died in Russia, and invented his salad in Russia as a chief of a russian restaurant.

Even the french agree: “Lucien Olivier est un chef russe d’origine franco-belge” - from Wikipaedia.

Also:

“Nationalité - russe”