Two Cooked Foods– On the eve of Pesach in the Beis Hamikdash in Jerusalem, two sacrifices (Korban Pesach and Korban Chagigah) were offered and their meat roasted and eaten at the Seder meal. After the destruction of the Temple, the Sages instituted the practice of placing two kinds of cooked foods on the Seder plate, one to commemorate the meat of the Pesach offering and one to commemorate the meat of the Chagigah offering.
There is a debate amongst the Amoraim in the Gemara (Pesachim 114b) what type of foods should be used. Rav Yosef maintains that since the two cooked foods are meant to commemorate the Pesach and Chagigah animal sacrifices, they must be meat dishes. Ravina disagrees and maintains that only one of the foods needs to be meat, the other can be any cooked food. The Rambam (Chametz Umatza chapter 8) follows the view of Rav Yosef. However, the Shulchan Aruch (473:5) follows the view of Ravina and one need not place two meat dishes on the ka’arah. The halacha follows this view. The custom has developed to use a shankbone to symbolize the Korban Pesach and an egg to symbolize the Korban Chagigah. [It should be noted that Rav Chaim Soloveichick zt”l followed the view of the Rambam by placing two meat dishes on the Seder plate. He also placed an egg there to fulfill in accordance with the common custom.(Haggada Shai Latorah page 35)]
Shankbone– The reason that the shankbone is used is that, aside from recalling the Korban Pesach, it also corresponds to the human arm, symbolizing the “outstreched arm” of Hashem. (M.B. 27)
Although the Shulchan Aruch and its commentaries write that the custom is to use a shankbone, many Chassidim actually use parts of a chicken in stead. The custom of Belz Chassidim is to use the drumstick of a chicken. The custom of Ropshitz, Sanz, Amshinav, Spinka, Satmar and Sigat Chassidim it to use a chicken wing. And the custom of Chabad, Karlin and Ziditchov Chassidim is to use a chicken neck.(Netai Gavriel Pesach 2:69:1) I believe that the reason that these chassidim chose to use a chicken and not the standard shankbone is in order to avoid any similarity to the korban pesach, which may not be sacrificed outside of the Beis Hamikdosh.
If one does not have a shankbone he should take any other meat, even not on the bone.(M.B. 27)
A bone without meat does not constitute as a dish. Therefore, one must make sure that there is meat on the bone. (Ran on the Gemara Pesachim) The custom of Chabad Chassidim is to remove most of the meat and only leave over a small amount of meat. This is again in order to avoid any similarity to the Korban Pesach.
The Shulchan Aruch (473:4) writes that the shankbone should be roasted over the fire, in order to symbolize the Korban Pesach which was also roasted. The Magen Avraham cites the view of the Maharshal, Bach and Shelah that since the common custom is not to eat roasted meat at the Seder (since onlookers may think we are eating the Korban Pesach, which is forbidden), the meat should therefore be boiled in order to allow the family members to eat the meat from the ka’arah at the Seder. (This is indeed the custom of Stalin, Lelov and Nadvorna Chassidim to boil the meat and not to roast it. See Netai Gavriel page 338) The Taz disagrees with the view of the Maharshal and the Bach and he maintains that one may not eat meat off of the ka’arah even if it is boiled, since it appears as if one is eating the Korban Pesach (eating boiled meat not from the ka’arah is permitted). The common custom is to follow the view of the Shulchan Aruch and to roast the shankbone. (M.B. 28)
Harav Noach Isaac Oelbaum shlit”a writes that one should make sure to roast the meat over the fire and not on the metal grates, which are heated by fire. If one can not roast the entire shankbone directly over the fire, one should scrape off some of the meat, and roast it over the fire. (Haggadah Minchas Chein page 62)
As noted above, the shankbone is roasted over fire. Since the common custom is not to eat roasted meat at the Seder, one should not roast the shankbone on Yom Tov. The reason is that since it will (most likely) be left over until the Second Seder, in essence it will be considered preparing something on the first day of Yom Tov for use on the next. Rather one should roast it before Yom Tov. If one forgot to do so, he may roast it on Yom Tov as long as he eats it on the first day of Yom Tov. (M.B. 32)
The Chaya Adam writes that it is not proper to throw away the shankbone, it should be eaten on the second day of Yom Tov, by day. Indeed, in the Haggadah of Rav Chaim Kanievsky shlit”a (page 19), it states “Rav Chaim makes sure that the zeroa, the roasted bone that was placed on the Seder plate, is eaten on Yom Tov, to ensure that it will not go to waste, as that would be a disgrace for this item, which was used for a mitzvah.”
Many people roast the shankbone before Yom Tov and use the same shankbone for both sedarim. And in many cases the shankbone, after sitting out for two days has become repulsive. Care should be taken to avoid this (by the use of refrigeration between the two sedarim). Harav David Feinstein shlit”a writes, “Indeed, to my mind, one does not even fulfill the mitzvah to remember the Pesach sacrifice the second night if the shankbone is not fit to eat.” (Haggadah Kol Dodi page 30)
There are two reasons that we use an egg as the second cooked dish. A) The first reason is that the Aramaic word for egg (בֵיעָא) is related to the Aramaic word for desire (בָעָא)- God desired to take us out of Egypt with an outstretched arm. (M.B. 23) B) In addition, the egg is a mourners food. Therefore, an egg is used to symbolize our mourning for the destruction of the Beis Hamikdosh and our inability to offer the Korban Pesach.
The Tanaim (Pesachim 70a) disagree how the Korban Chagigah was prepared. According to the Sages the Korban can be either boiled or roasted. While according to Ben Teima the Chagigah must be roasted similar to the Korban Pesach. The Shulchan Aruch writes that the egg, symbolizing the Korban Chagigah, can be either boiled or roasted, in accordance with the view of the Sages that both preparations were permitted for the Chagigah. This is also the view of the Ben Ish Chai (Tzav 30) and is the custom of Chabad, Karlin, Lelov, Belz and Vishnitz Chassidim that the egg is boiled (Netai Gavriel page 340). The Rama however, notes that the common custom is to roast the egg, in order to also accomodate the view of Ben Teima. This is the common custom amongst Ashkenazim.
Although the Chagigah sacrifice was not brought on Shabbos [and was therefore not eaten Saturday nights], it is still customary on Saturday nights to place the egg symbolizing it on the Seder plate.(M.B. 22)