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.
seems Olivier was French/belgian as his name entail: https://en.wikipedia.org/wiki/Olivier_salad
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”