No, we are not. That's why I said that it's not an "idiom". You can read about this traditional ceremony here: https://goo.gl/Qq3RK5.
Basically: "When important, respected, or admired guests arrive, they are presented with a loaf of bread placed on a rushnik (embroidered towel). A salt holder or a salt cellar is placed on top of the bread loaf or secured in a hole on the top of the loaf."