After the meal at the Seder, one must eat at least a Ke’zayit of Masa, which we call the Afikoman. This Masa serves to commemorate the Korban Pesah which in the times of the Bet Ha’mikdash was eaten after the meal at the Seder.
The Ben Ish Hai (Rav Yosef Haim of Baghdad, 1833-1909) writes that it is preferable to eat two Ke’zetim of Masa for the Afikoman, as the meat of the Korban Pesah was eaten together with Masa. This is also the position of Hacham Bension Abba Shaul (Israel, 1923-1998). The Shulhan Aruch (Orah Haim 477), however, writes that one needs to eat only one Ke’zayit. Accordingly, Hacham Ovadia Yosef rules that one is required to eat just one Ke’zayit of Masa for the Afikoman, but those who wish to be stringent and are able to eat an additional Ke’zayit may do so.
We customarily eat for the Afikoman the piece of Masa that had been hidden earlier in the Seder. Of course, this piece of Masa will not suffice to supply a Ke’zayit for everybody at the Seder, and thus one should take additional Masa from the box on the table. Masa Shemura should be used for the Afikoman just as it is for the Masa eaten before the meal.
One must lean on his left side while eating the Afikoman, but if one ate the Afikoman without leaning, and it would be difficult for him to eat another Ke’zayit, he does not have to eat more Masa.
If after the meal a person washed Mayim Aharonim or announced, "Hav Lan Ve’nibrich" ("Let us recite Birkat Ha’mazon"), and he then realized that he had not eaten the Afikoman, he should eat the Afikoman before Birkat Ha’mazon. Normally, when a person decides to eat more bread after he had washed Mayim Aharonim or announced, "Hav Lan Ve’nibrich" he must perform Netilat Yadayim and recite "Ha’mosi" before he eats. In the case of Afikoman, however, one washes without a Beracha and does not recite "Ha’mosi." The Shulhan Aruch explains that at the Seder, we are guests at the Almighty’s table, and thus even if we prepare to recite Birkat Ha’mazon, He determines that the meal does not end before we eat the Afikoman. Therefore, although one should repeat Netilat Yadayim, he does not repeat the Berachot.
One must ensure not to eat so much during the meal that he will be unable to eat at least a Ke’zayit for the Afikoman.
The Afikoman should preferably be eaten before Hasot (midnight as defined by Halacha). This year (5775), Hasot in Brooklyn occurs at around 1am.
The Rama (Rav Moshe Isserles of Cracow, 1525-1572) rules (477:1) that one should also try to recite the Hallel before Hasot, as there is one view among the Rishonim that Hallel must be recited after Hasot. Hacham Bension Abba Shaul rules that if one completes Hallel after Hasot, he cannot recite the concluding Beracha of "Melech Mehulal Ba’tishbahot," given the uncertainty as to whether the Misva can be fulfilled at that point ("Safek Berachot Le’hakel"). Hacham Ovadia Yosef, however, rules (at the end of Hazon Ovadia – Teshubot, vol. 2) that the Beracha is recited in such a case. He notes that according to some opinions, the concluding Beracha does not refer specifically to the Misva of Hallel, but is rather a general expression of praise to Hashem. Moreover, there is an opinion that the Misvot of the Seder can be fulfilled throughout the night. Hacham Ovadia further notes that there were great Sages, including the Hatam Sofer, who recited Hallel after Hasot at the Seder without any concern. For these and other reasons, one may recite the concluding Beracha even if he recites Hallel after Hasot.
In many Haggadot, the word "Amen" appears after the concluding Beracha at the end of Hallel ("Melech Mehulal Ba’tishbahot Amen"). This text is incorrect. We add "Amen" at the end of a Beracha only if it concludes a series of Berachot, which is not the case with regard to this Beracha at the end of Hallel at the Seder. We do not recite the introductory Beracha to Hallel at the Seder (as we rely on the Beracha recited over Hallel in the synagogue), and thus the concluding Beracha of "Melech Mehulal Ba’tishbahot" stands on its own and does not conclude a series of Berachot. As such, "Amen" should not be recited.
