Karpas

Vegetable (usually parsley) is dipped into salt water during the seder. The salt water represents the tears shed during Egyptian slavery. The dipping of a vegetable as an appetizer is said to date back to biblical times. It may now be identified with biblical description of the Hebrew slaves marking their doorposts at the time of the first Passover. A bunch of hyssop was to be dipped in the blood of the paschal lamb and used to strike the lintel and the doorposts (Exodus 12:22) so that the tenth plague (death of the firstborn) would not be visited upon their households.