The Torah commands in the Book of Shemot (12:9), “Al Tochelu Mimenu Na U’bashel Mebushal Ba’mayim” – that one may not eat the meat of the Korban Pesah when it is in a state of “Na,” or if it had been boiled in water (or any other liquid). The word “Na” is commonly translated as “raw,” but in truth, it means “not fully roasted.” If one eats the meat of the Korban Pesach when it is completely raw, he fails to fulfill the affirmative command to eat the meat roasted, but he does not violate the prohibition against eating it “Na,” because “Na” refers to meat which has begun to be roasted over fire but has not yet been fully roasted.
More specifically, “Na” refers to meat which has yet to be roasted to the point of “Ma’achal Ben Derusai” – the point at which it is just barely edible. Once the meat of the Korban Pesach has reached the minimum level of edibility, it is no longer considered “Na,” and thus it may be eaten. Both sides of the meat must be roasted until the point of “Ma’achal Ben Derusai” for the meat to be permissible for consumption (just as on Shabbat, one who cooks meat is not in violation of Shabbat unless both sides reach the level of “Ma’achal Ben Derusai”).
Like all the Misvot relevant to the Korban Pesach, this Misva applies to both men and women.
The Sefer Ha’hinuch explains that the reason behind the Misva is that as we celebrate our nation’s Exodus from Egypt, we should conduct ourselves as distinguished noblemen. In ancient times, the masses, who could not afford to eat large quantities of meat, would boil their meat, even though roasted meat tastes better, because roasting causes the meat to contract, whereas boiling has the effect of expanding it. Only the wealthy aristocracy, who could afford large quantities of meat, would roast their meat to enjoy the enhanced taste, because it did not matter to them that the meat contracted over the process of roasting. On Pesach, as we celebrate our freedom from bondage, we are to conduct ourselves in a regal manner, and so the Torah forbids eating the meat of the Korban Pesach in a state other than fully roasted.
Additionally, the Sefer Ha’hinuch writes, meat can be prepared more swiftly by roasting than by boiling. Thus, roasting the meat of the Korban Pesach serves to commemorate the “Hipazon” – the haste with which Beneh Yisrael left Egypt, when they needed to prepare the meat of the sacrifice in the quickest way possible.
The Rambam, in his listing of the Misvot, includes under this prohibition both eating meat of the Korban Pesach which is not fully roasted, and meat of the Korban Pesach which was boiled. The Ramban, however, disagrees with this classification, and lists two separate prohibitions: one forbidding eating meat of the Korban Pesach which has not been fully roasted, and another forbidding eating meat of the Korban Pesach which had been boiled. Therefore, if one ate both kinds of meat – a piece which is not fully roasted, and a piece which had been boiled – then according to the Rambam, he is liable to just a single set of Malkut (lashes), whereas according to the Ramban, he is liable to two sets of Malkut.
An interesting question arises according to the Ramban in the case of meat of the Korban Pesach which was partially roasted, and, before it reached the point of “Ma’achal Ben Derusai,” it was taken off the fire and then boiled in water. If one would then eat this meat, would he be in violation of both prohibitions, or only a single prohibition? Of course, this question does not arise according to the Rambam, who in any event includes both partially roasted meat and boiled meat under a single prohibition. But according to the Ramban, who maintains that these constitute two separate prohibitions, for how many violations would one be liable if he partakes of meat of the Korban Pesach which was both partially roasted and boiled in water?
At first glance, we would apply to this case the rule of “En Issur Hal Al Issur” (literally, “a prohibition cannot descend upon a [different] prohibition”) – that once something is forbidden by force of one prohibition, it cannot then become subject to another prohibition. Seemingly, once the meat becomes forbidden because it is partially roasted, it cannot then also become subject to a separate prohibition when it is boiled, and thus one who eats this meat would be liable for just a single violation – eating partially roasted meat. The Minhat Hinuch, however, notes that the rule of “En Issur Hal Al Issur” is not applicable to this case, because Halacha makes an exception in a situation of “Issur Mosif” – where the second prohibition is more inclusive than the first. If the second prohibition expands the prohibition beyond the parameters of the first prohibition, then the object in question indeed becomes subject to both prohibitions. In the case under discussion, boiling the meat has the effect of rendering it permanently forbidden. Partially roasted meat, while currently prohibited for consumption, can become permissible if it is left to continue roasting on the fire. But once it is boiled in water, its prohibited status becomes permanent. Since the second prohibition contributes an additional element to the meat’s prohibited status, it takes effect, and the meat should thus become forbidden by force of both prohibitions – the prohibition against eating partially roasted meat of the Korban Pesach, and the prohibition against eating boiled meat of the Korban Pesach.
On the other hand, the Minhat Hinuch writes, one might argue that boiling the partially roasted meat has the effect of erasing the meat’s prior history, so-to-speak, such that it is no longer considered to have been partially roasted. If so, then even according to the Ramban, a person who eats this meat would be liable for only a single violation – eating boiled meat of the Korban Pesach. The Minhat Hinuch leaves this question unresolved.