In Yiddish, gizzards are referred to as "pipik'lach", literally meaning navels. The gizzards of kosher species of birds have a green or yellowish membrane lining the inside, which must be peeled off before cooking, as it lends a very bitter taste to the food. In traditional Eastern European Jewish cuisine, the gizzards, necks and feet of chickens were often cooked together, although not the liver, which per kosher law must be broiled. Kosher butchers often sell roasting chickens with the gizzard, neck and feet butchered and left in the cavity to be used for making chicken soup.