BOB ABERNETHY, anchor: In addition to Holy Week for Christians, for Jews the eight-day celebration of Passover begins with the Seder Monday night (April 5). We talked about the food of the Seder with cookbook author Joan Nathan.

JOAN NATHAN (Author): Passover is my favorite holiday. It is not only the narration of the exodus of the Jews from Egypt, from slavery to freedom, but it's also a celebration of spring.

Not only does it link us to Egypt, to Israel, to the land of Israel, but it also links us to our own generations. For example, at my own Seder we have many recipes that my late mother-in-law made from Poland.

In the Book of Exodus, it tells us that during Passover, during eight days, you should not use any leavened items and leavened bread. Today it would mean pizza, pasta, corn, beans, rice, even mustard seed -- things that are leavened or fermented.

But, Judaism is very complicated. Many Sephardic Jews will eat all kinds of beans, but Ashkenazic Jews won't. Rice -- Sephardic Jews might eat rice; Ashkenazic Jews won't. Any kinds of grains -- forget grains. Any kinds of rice, pasta, pizza -- anything like that cannot be used at Passover.

Every single food -- that's the other thing -- on the Passover Seder plate has a dual symbolism and probably a tri-symbolism that makes it even richer, because it's something you can talk about.

On the Seder plate, there's the harosset, which is one of my favorite parts of the Passover meal, which is a paste made out of fruit and nuts. It symbolizes the mortar that the Jews used when they were slaves in Egypt.

I know of maybe a dozen different harosset recipes from all over the world, and at my Seder I have at least five because I think it's a way of teaching the diaspora, how Jews wandered.