It is the liver of ducks (foie gras de canard) or geese (fois gras d’Oie).

一般指的是鸭或鹅的肝脏（称为鸭肝或鹅肝）。

youdao

The homemade fois gras (goose liver on toast) with sweet jam was deliciously tender, explaining its a popularity among regular patrons.

自制的鹅肝酱配上甜甜的果酱温和深受食客亲睐。

youdao

Glad to be proven wrong, I've found Le 5 Sens to be a welcome refuge from Chinese cuisine for anyone wanting to treat themselves to a bit of fois gras and some French wine.

庆幸这只是一个误解，乐尚是一个暂时离开中餐，用一点鹅肝酱和一点法国酒犒劳自己的地方。

youdao

They launched at Smorgasburg, serving mayo on French fries and testing flavors like coffee, fois gras and emu egg.

WSJ: Yes, Artisanal Mayo

And what the French want to know is where to get a good piece of fois gras and a good bottle of Bordeaux.

FORBES: What Gives? Bread Or Circus?