▁more ▁fo ie ▁gr as ; ▁if ▁term ed ▁ ▁(" with ▁pieces "), ▁it ▁must ▁contain ▁at ▁least ▁ 5 0 % ▁fo ie ▁gr as ▁pieces ▁for ▁go ose , ▁and ▁ 3 0 % ▁for ▁du ck . ▁ ▁Additionally , ▁there ▁is ▁, ▁ ▁( e ither ▁must ▁contain ▁ 5 0 % ▁or ▁more ▁fo ie ▁gr as ), ▁ ▁( must ▁contain ▁ 7 5 % ▁or ▁more ▁fo ie ▁gr as ), ▁and ▁other ▁prepar ations ▁( no ▁legal ▁oblig ation ▁established ). ▁ ▁Ful ly ▁cook ed ▁prepar ations ▁are ▁generally ▁sold ▁in ▁either ▁glass ▁containers ▁or ▁metal ▁can s ▁for ▁long - term ▁pres ervation . ▁Wh ole , ▁fresh ▁fo ie ▁gr as ▁is ▁usually ▁un available ▁in ▁France ▁outside ▁the ▁Christmas ▁period , ▁except ▁in ▁some ▁produ cers ' ▁mark ets ▁in ▁the ▁producing ▁regions . ▁Fro zen ▁whole ▁fo ie ▁gr as ▁sometimes ▁is ▁sold ▁in ▁French ▁super mark ets . ▁ ▁Wh ole ▁fo ie ▁gr as ▁is ▁readily ▁available ▁from ▁g our met ▁ret ail ers ▁in ▁Canada , ▁the ▁United ▁States , ▁Hung ary , ▁Argentina ▁and ▁regions ▁with ▁a ▁size able ▁market ▁for ▁the ▁product . ▁In ▁US , ▁raw ▁fo ie ▁gr as ▁is ▁class ified ▁as ▁Gra de ▁A , ▁B ▁or ▁C . ▁Gra de ▁A ▁is ▁typically ▁the ▁highest ▁in ▁fat ▁and ▁especially ▁su ited ▁for ▁low - temper ature ▁prepar ation , ▁because ▁the ▁ve ins ▁are ▁relatively ▁few ▁and ▁the ▁resulting