Shiur #06: Cooking in a Tertiary Vessel
LAWS OF SHABBAT: COOKING
By Rav Yosef Zvi Rimon
By Rav Yosef Zvi Rimon
Translated by Rav Yoseif Bloch
Shiur #06: Cooking in a Tertiary Vessel
Is one allowed to prepare a teabag in a keli shelishi?
May one make instant foods on Shabbat?
As we have seen, the Ashkenazic custom is to be concerned about cooking in a keli sheini (secondary vessel) and not to put any food into them, since one should be concerned about the issue of kallei bishul (food items that are easily cooked), which may end up getting cooked even in a keli sheini. Should one be concerned about bishul in a keli shelishi (tertiary vessel) as well? Is it allowed, for example, to prepare tea in a keli shelishi?
According to the Peri Megadim (Eshel Avraham 318:35), this is permissible:
On Shabbat, [even] according to the view in paragraph 5 [of Shulchan Arukh OC 318], that it is forbidden to put bread in a keli sheini, concerning tea in a keli shelishi and the like one should be lenient.
The words of the Peri Megadim are cited by the Mishna Berura (318:47) as conclusive. This is also what Rav Moshe Feinstein (Iggerot Moshe, part 4, bishul, 15) writes:
Now the tea leaves are not cooked while they are being processed, but rather dehydrated, so may one prepare tea in a keli shelishi on Shabbat?
Answer: In my humble opinion, it is not feasible to say that there are things that may be cooked in a keli shelishi, because we have found only regarding a keli sheini that it can cook some things, and naturally we have no choice but to forbid everything; however, we not found that this true of a keli shelishi.
What is written in the Arukh Ha-shulchan that we may see with our own eyes that tea cooks in a keli shelishi is not understandable. What we see with our own eyes is that the waters grow red, but this is not an issue of bishul, for even [a teabag in] cold water will turn [the water] red as time passes, all the more so warm water that is not yad soledet bo (scalding), and this is not an issue of bishul.
Take hold of yourself, because what our eyes see is not significant. After all, we see that concerning salt, it makes no difference [and we can taste its effect] whether we put it in lukewarm or in water that is yad soledet bo. Nevertheless, the law follows Rav Nachman (42b), and even a keli rishon does not cook salt
So it is with tea leaves: the fact that the water is colored with a bit of heat is not an issue of bishul. In fact, it may belong in the category of those things that are difficult to cook [the opposite of kallei shul]! Therefore, we should say nothing of our own accord, but rather rely on tradition, and naturally it is like all other things: in a keli sheini, it is doubtful [so we forbid cooking in it], but in a keli shelishi, one should allow it.
Rav Feinstein writes that the idea of foods being easily cooked is only raised in the context of a keli sheini, and because of this we are customarily stringent, avoiding putting any uncooked food in it, out of concern that this food may be one of the kallei bishul. In terms of a keli shelishi, on the other hand, we have never found anywhere that there is a concern of bishul, and there is no evidence that any food can be cooked inside it.
Granted, the Arukh Ha-shulchan (318:28) claims that tea certainly gets cooked even in a keli shelishi, because we see with our own eyes that the water becomes red (therefore, in his view, there is a biblical prohibition to put tea leaves even in a keli shelishi); however, Rav Feinstein determines that we should not rely on our eyes in this area. In his view, what we may observe, namely the darkening of the water in a keli shelishi as the tea leaves steep, is not a proof that the tea is being cooked, because even if we put tea in cold water, the water will eventually turn red. Thus, the color change is not an indication of bishul.
Indeed, he continues, this is true of salt as well: even though we sense the taste of salt when we dissolve it in a keli rishon, in any case, the letter of the law allows one to add salt to a keli rishon (we will discuss this in a later shiur). In other words, our perception that the tea is being cooked is not factually correct.
Therefore, we must determine when bishul takes place based solely on the words of the Talmud, not our senses, and in the Gemara it does not say anywhere that one can cook food in a keli shelishi.
However, the Chazon Ish (52:19) asks a very strong question against those who are lenient regarding cooking in a keli shelishi:
When it comes to a keli shelishi, in a situation in which using a keli sheini is prohibited, e.g. for bread or onions according to the stringent Acharonim, the Mishna Berura writes that the Peri Megadim inclines to be lenient. Furthermore, we have found no source to differentiate between a keli sheini and a keli shelishi, and anything that will be cooked in a keli sheini will be cooked in a keli shelishi, and it depends only on the temperature, whether it is yad soledet bo or not
Nevertheless, since it is merely a stringent view, they may follow their custom; after all, for the most part, a keli shelishi is not yad soledet bo, and therefore they were lenient about this.
According to the Chazon Ish, there is no reason to differentiate between a keli sheini and a keli shelishi: if there are foods that will become cooked in a keli sheini, they will presumably become cooked also in a keli shelishi that is yad soledet bo. In a previous shiur we mentioned that the Tosafot explain that a keli sheini is special on account of its cold walls. Naturally, if we are stringent regardless in the case of a keli sheini, since we follow the temperature of the water and not the walls, there is no further reason to differentiate between a keli sheini, keli shelishi or even if we were to continue on to a keli revii (quaternary vessels), and only the temperature counts if it is at the level of yad soledet bo, there is an issue of bishul.
Limitations of Stringency
However, the Chazon Ish concludes by saying that even though there is no reason to differentiate between a keli sheini and a keli shelishi, since kallei bishul may not be put in a keli sheini, and including everything in kallei bishul follows a stringent view, there is some logic in the common practice, because there is no such stringent custom for a keli shelishi. However, the foods that are definitely known as kallei bishul may not be put even in a keli shelishi, since these may not be put in a keli sheini by the letter of the law, not a stringent view, and as regards actual bishul, there is no reason to differentiate between keli sheini and keli shelishi.
The question of the Chazon Ish appears strong, but it appears that there is good logic to defend the lenient view. In a previous shiur, we saw the view of Rashi (39a, s.v. De-sharei) explaining the view allowing cooking in the sun: this is not the way of cooking. Indeed, since we are not accustomed to cook in the sun (based on the different explanations we have cited there) there is no prohibition of bishul in the sun.
For our issue, it may be that the focus of the distinction between keli sheini and keli shelishi is the common custom. Most foods we cook in a keli rishon; some foods, such as tea, coffee, baby formula, etc., are commonly cooked in a keli sheini; while in a keli shelishi, one is not accustomed to cook at all. Naturally, we may say that even if on a practical level the foods that would cook in a keli sheini would also cook in a keli shelishi, there is no prohibition to cook them in a keli shelishi, because this is not derekh bishul, and it does not fall within the boundaries of the melakha.
Some are Stringent and Some are Lenient
In practice, there are those who are stringent and do not prepare tea even in a keli shelishi, and many are also stringent about other food items that appear to be easily cookable. This is the ruling found in Shemirat Shabbat Ke-hilkhata (1:57): One may not put a raw egg, tea leaves or salted fish in a keli shelishi as long as the water is yad soledet bo.
On the other hand, there is a good basis for the view of those who are lenient, following Rav Feinstein, maintaining that there is no prohibition of bishul in a keli shelishi at all, as appears to be the simple meaning of the words of the Mishna Berura. In any case, one who is stringent will prepare tea essence before Shabbat; this will allow one to prepare tea even in a keli sheini, even if the essence is cold, as will be explained in a later shiur.
Preparing Instant Food
As we have said, according to the lenient view, one is allowed to put anything in a keli shelishi. According to this, one may prepare instant soup or instant food on Shabbat in a keli shelishi. When we are talking about instant food, one may combine this with the fact that generally these portions are almost cooked (perhaps, in actual fact, already fully cooked) with the view of the many Rishonim who believe that there is no prohibition of bishul after the food has already been cooked to the measure of ben Derusai (as we discussed in our first shiur). Indeed, it is not desirable that preparing instant food become a habit, as this feels like bishul; nevertheless, when there is a need, one may be lenient about this.
We should note that preparing instant food sometimes involves a problem of the prohibition of lash (kneading), as we shall see in a future shiur.
 According to this view, since there are food items that one is accustomed to cook in a keli sheini, a keli sheini would be considered a heat source for the issue of the prohibition of bishul, and one should not put in it any food that could conceivably become cooked, even if one does not normally cook this food in a keli sheini. (One should not be lenient except as regards things that practically cannot be cooked in it, e.g., water, oil and spices, as we have noted above.) Only a keli shelishi, in which we are unaccustomed to cook any food, is totally excluded from the prohibition of bishul.
 We should add that regular tea is normally roasted, so that there is more of a reason to be lenient about putting it in a keli shelishi, as one may enlist the view of those who believe that cooking after baking is irrelevant (there will be a future shiur on the topic of ein bishul achar afiya whether cooking a food previously baked constitutes bishul). On the other hand, herbal tea is actually dried in the sun, and therefore to be lenient about preparing it in a keli shelishi, one must rely on the view of Rav Feinstein.