1) DIPPING THE KARPAS INTO CHAROSES
OPINIONS: The Mishnah says that during the Seder, Chazeres (Maror) is brought to the table before the Matzah. The Gemara explains that this refers to the Karpas which is eaten before the meal in order to arouse the curiosity of the children. The Gemara explains that one is not required to eat Chazeres for Karpas; any vegetable may be used. The Mishnah mentions Chazeres to teach that even when the only vegetable available is Maror, one should still use it for Karpas in order to arouse the curiosity of the children.
Does the vegetable used for Karpas need to be dipped into Charoses like the vegetable used for Maror?
(a) TOSFOS, in the name of RABEINU TAM, says that one should dip Maror in Charoses in order to get rid of the danger of the poison in the Maror ("Kafa"). Therefore, only if one uses actual Maror for Karpas does he have to dip it into Charoses; if he uses any other vegetable, he need not dip it.
The ROSH writes that Rabeinu Tam made a point not to dip the Karpas into Charoses, but rather into salt water or vinegar, because one should not fill his stomach with Charoses before he eats it later for the sake of the Mitzvah.
(b) Tosfos cites the Sidur of RASHI and the MACHZOR VITRI who maintain that a person should dip any vegetable used for Karpas -- whether it is Chazeres or not -- into Charoses. This opinion, which the TUR (OC 273) cites in the name of RAV AMRAM GA'ON, is also the opinion of the RAMBAM (Hilchos Chametz u'Matzah 8:2).
(c) The ROSH rules that it is not necessary to dip even Chazeres into Charoses when it is used for Karpas. This is also implied by the RASHBAM. The TUR records this opinion and writes that since this is not the Maror that is eaten for the Mitzvah, there is also no Mitzvah to dip it into Charoses.
The Rosh asks that this reasoning makes sense according to the opinion that says that the reason to dip into Charoses is because the Charoses itself is a Mitzvah. However, everyone agrees with the additional reason to dip Maror into Charoses -- the danger of "Kafa," the poison in Maror. Accordingly, one should be required to dip the Maror into Charoses the first time as well.
RABEINU YONAH (cited by the Rosh) answers that throughout the year, people eat Maror without Charoses. Even though there is a slight risk to eat it plain, each person is free to take precautionary measures as he sees fit. However, when the Rabanan established the Mitzvah of Maror, they were concerned for everyone's well-being and required that one dip the Maror into Charoses. (See Insights to Pesachim 110:2 for further discussion of this topic.)
HALACHAH: The DARCHEI MOSHE quotes the AGUR who says that the author of the AGUDAH would put a little Charoses into the vinegar and dip the Charoses into the vinegar to satisfy all of the above-mentioned opinions.
The BEIS YOSEF, however, writes that everyone agrees that one is not required to dip other vegetables into Charoses. The question is only whether one is allowed to dip them into Charoses. Therefore, he writes that it is best to avoid the issue and dip the vegetable used for Karpas into vinegar. The SHULCHAN ARUCH (OC 273:6) therefore rules that one should dip Karpas into vinegar. The MISHNAH BERURAH adds that one may use salt water as well, which is the common practice today.
2) HALACHAH: KITNIYOS
QUESTION: The Gemara relates that Rav Huna would place rice as one of the cooked dishes on the Seder plate. Today, rice is considered Kitniyos and is not eaten during Pesach by members of the Ashkenazic community. It is clear that this practice began after the times of the Gemara. When, and why, did it start?
ANSWER: The HAGAHOS MAIMONIYOS (cited by the BEIS YOSEF OC 453), and the MORDECHAI (#588) cite the SEMAK who records the custom not to eat Kitniyos, such as rice and other legumes, during Pesach. This stringency is not due to concern that rice might become Chametz, because it is clear from the Gemara's conclusion that rice is unable to become Chametz. Rather, there are other reasons for the stringent practice to avoid rice and other legumes on Pesach:
(a) These legumes sometimes have wheat and other types of grains mixed in with them, and it is impossible to distinguish between the legumes and the wheat. When the legumes are cooked, the wheat that is mixed with them will become Chametz.
(b) The flour of Kitniyos can be used to make dough and baked goods, even bread (such as rice bread). The Rabanan were concerned that unlearned people might confuse a Kitniyos dish with a grain dish and permit real Chametz on Pesach. Even though this was not a concern in the times of the Gemara, the Rabanan of later generations saw that the people had become less knowledgeable. Therefore, they instituted the practice not to eat Kitniyos at all on Pesach.
(c) The BI'UR HALACHAH (beginning of OC 453) cites RABEINU MANO'ACH who pointed out that during years of drought, some species of wheat grow in odd shapes, and they could appear indistinguishable from Kitniyos. Therefore, the Rabanan instituted that all Kitniyos are prohibited on Pesach.
HALACHAH: The SEMAK, SEFER HA'TERUMAH, and the MORDECHAI are stringent and prohibit Kitniyos on Pesach. This is the custom as recorded by the REMA (OC 453:1), and it is the practice of the Ashkenazic community today.
The TUR, however, writes that there is no basis for this stringency. The BEIS YOSEF writes that he saw only Ashkenazim conduct themselves stringently, and therefore he rules leniently for Sefardim.
Since the custom to refrain from Kitniyos is a later institution, even the Ashkenazim do not treat Kitniyos as complete Chametz, and they practice certain leniencies (for example, a mixture of Kitniyos with other food is, b'Di'eved, permissible, as the Rema writes).