Halakhah su Esodo 12:9

To not eat the Pesach sacrifice uncooked or boiled: To not eat from the meat of the Pesach sacrifice uncooked or boiled, but rather roasted with fire, as it is stated (Exodus 12:9), "Do not eat any of it raw (na), or surely boiled with water, but only roasted with fire." The content of this is not to eat it before it is completely cooked, even if roasted. And this is the explanation of na (Pesachim 41a) - as the meat that the process of heating has begun upon and is roasted a bit but is not [yet] fit for a person to eat is still called na. But when it is completely raw - whereby the heating process has not begun upon it at all - it is not included in the prohibition of na; such as to administer lashes, because of "Do not eat any of it na." But [it] is [still] prohibited by the Torah, as the Torah prohibited more generally anything that is not roasted with fire. And the explanation of "boiled" (literally, cooked) is that it is boiled in water or in any liquid or fruit juice; as it is stated, "surely boiled" - [to] include all [of these].

The second type is when one negative commandment comes to forbid several matters that are connected to one another - and that is that He says, "Do not do such and such." And this type is divided into two divisions. For included in it is that about which they said in the Talmud, that he is liable for lashes on each and every one of the connected matters. But [also] included in it is that about which they said that he is only liable once, since it is a general negative commandment. And those negative commandments about which they explained that one is liable for each and every one of them - they are the ones that we count each and every one as a separate commandment; whereas that about which they explained that one is only liable once for all of them is counted as a single commandment. This is according to that which we established in this principle - that under no circumstances is one given two [sets of] lashes for one negative commandment . So when, in the explanation, they made one liable for each and every connected matter - to give lashes for each and every one of them when they were all done at once, to give several [sets of] lashes - we perforce know that they are several categories; and that each one should be counted separately. And I will mention several examples from both divisions until the intended matter becomes totally clear. And that is His, may He be blessed, saying, about the lamb of the Pesach sacrifice, "Do not eat any of it raw or boiled in any way with water" (Exodus 12:9) - a negative commandment, which we count as one commandment. And we don't count, do not eat it raw, as one commandment; and do not eat it boiled, as another commandment. For He did not specify a separate negative commandment for each matter, to say "Do not eat any of it raw; and not boiled in any way" - but rather one negative commandment came to include both matters; and the one matter was appended to the other. And in the second chapter of Pesachim (Pesachim 41b), they said, "Abbaye said, 'If he ate it raw, he is given two [sets of] lashes; raw and boiled, he is given three." And that is because he holds that we give [distinct sets of] lashes for general negative commandments. So when he ate it raw, he transgressed two negative commandments: One of them is, "Do not eat any of it raw"; and the second [set of] lashes is from the general principle - as He is saying, do not eat it when it is not roasted, and he has already eaten it when it is not roasted. And according to his opinion, when he eats it raw and boiled, he gets three [sets of lashes] - one because he ate it raw; the second because he ate it boiled; and the third because he ate it when it was not roasted. And over there, they said about this statement, "But Rava said, 'One does not receive lashes for a general negative commandment.' Some say, at any rate, one [set of] lashes he does receive. And some say he does not receive even one [set of] lashes, as the negative commandment he transgressed is not specific to it, as is the negative commandment against muzzling." That means to say, like that which He, may be exalted, said (Deuteronomy 25:4), "You shall not muzzle an ox while it is threshing" - which is one negative commandment that prohibits one matter. However for this negative commandment, which prohibits two things - raw and boiled - we do not give lashes. And you already know that it was clarified in the Gemara (Sanhedrin 63a), that we do not give lashes for a general negative commandment. And hence the statement of Abbaye is rejected; and the truth is that he is given one [set of] lashes: Whether he ate any of it raw and boiled, [just] raw or [just] boiled, he is only given one [set of] lashes. And so we shall count His, may He be exalted, saying, "Do not eat any of it raw or boiled," as one commandment. And there, it is also stated, "Abbaye said, '[If a nazirite] ate a grape skin, he receives two [sets of lashes]; a grape pit, he receives two; a grape skin and a grape pit, he receives three. But Rava said, 'One does not receive lashes for a general negative commandment'" - meaning to say, "from anything that is obtained from the grapevine" (Numbers 6:4), for which Abbaye thinks we give lashes. And they also said in the fifth chapter of Menachot (Menachot 58b), "One who offers leaven and honey on the altar - Abbaye says, 'He receives lashes on account of leaven; he receives lashes on account of honey; he receives lashes on account of a mixture of leaven; and he receives lashes on account of a mixture of honey'" - meaning to say that His saying (Leviticus 2:11), "any," is including two things: That he not offer it by itself; and that he not offer a mixture of it, whatever the quantity [of what is mixed with it] may be. And this is all according to the principle of his approach - as he holds that we give [distinct sets of] lashes for general negative commandments. And it is stated there, "But Rava said, 'One does not receive lashes for a general negative commandment.' Some say, at any rate, one [set of] lashes he does receive. And some say he does not receive even one set of lashes, as the negative commandment he transgressed is not specific to it, as is the negative commandment against muzzling."

Iggerot Mosheh's analysis of Rashi's view leaves a serious question unresolved. As recorded in Exodus 12:9, the paschal sacrifice must be roasted and cooking the sacrifice in water is explicitly forbidden. The Gemara, Pesaḥim 41a, declares that cooking the paschal sacrifice in the thermal "waters of Tiberias" does not constitute a transgression of the negative commandment prohibiting cooking in water. Eglei Tal, Melekhet Ofeh, sec. 44, notes the obvious difficulty. If cooking by means of the heat of the sun is merely an uncommon or unusual mode of cooking it must nevertheless be categorized as being intrinsically a form of cooking. Unlike the rule with regard to Sabbath prohibitions, unusual forms of cooking are included in the prohibition regarding preparation of the paschal offering.¹⁷See, however, R. Elchanan Wasserman, Koveẓ Shi ‘urim, Ketubot 60a, who asserts that unusual acts are not only outside the ambit of Sabbath prohibitions but are also excluded from other biblical prohibitions. Thus, he argues, there is no biblical prohibition against cooking the paschal offering by means of solar heat. The same is true with regard to heat derived from the sun: Just as cooking in the “waters of Tiberias” on Shabbat is not biblically forbidden since the heat is derived from an unusual source so is cooking the paschal sacrifice in the “waters of Tiberias” excluded from the biblical prohibition. Cf., R. Benjamin Silber, Oz Nidberu, I, no. 34. If so, cooking the paschal sacrifice in the "waters of Tiberias" should constitute a transgression of the prohibition against cooking the sacrificial animal. Eglei Tal explains that, in terming solar cooking an "unusual" form of cooking, Rashi intends to indicate that cooking by means of solar heat is intrinsically different from conventional cooking, i.e., for halakhic purposes, solar heat and heat of a fire are regarded as qualitatively different. Hence, preparation of food by means of solar heat does not constitute "cooking," not because it is not analogous to the cooking performed in the construction of the Tabernacle, but because, by definition, it is not "cooking." There can be no question that, according to Eglei Tal, microwave cooking is similarly, by definition, not to be regarded as cooking; microwaves are even less similar in nature to a flame than are solar rays.¹⁸See also R. Gedaliah Rabinowitz, Torah she-be-’al Peh, XXIV (5743), who attempts to explain the “unusual” nature of solar cooking in another manner.