Hillel's sandwich

During the Passover Seder (the annual commemoration of the Exodus from Egypt), one re-enacts ancient customs in the Haggadah. In the section of Korech, or 'sandwich', participants are instructed to place bitter herbs between two pieces of matzo and eat them after saying in Hebrew: This is a remembrance of Hillel in Temple times—This is what Hillel did when the Temple existed: He enwrapped the Paschal lamb, the matzo and the bitter herbs to eat them as one, in fulfillment of the verse, "with matzot and maror they shall eat it." (Numbers 9:11) This sandwich apparently refers to traditional soft matzot rather than modern crisp matzot, and so would have borne a striking resemblance to a modern shawarma.[12] In modern times, when there is no paschal lamb, Ashkenazi practice is to emulate this by making a matzo, maror, (horseradish or lettuce) sandwich. Philo has called this sandwich a "moral migration from wickedness to virtue. Repentant sinners at first brood bitterly (maror) over their past misdeeds. Then matzah, the healing food, brings them to humility and contentment."[12]

haggadah Section: Koreich
Source: https://en.wikipedia.org/wiki/Hillel_the_Elder#Hillel.27s_sandwich