May one prepare ground coffee in a k'li sheini?

In the previous shiur we learned that one may prepare Nescafe in a k'li sheini because Nescafe is cooked during the manufacturing process. Ground coffee is not brewed, only roasted, and therefore the same rule applies to ground coffee as is applied to bread; it should only be prepared in a k’li sh'lishi. (There are those who are stringent and will not prepare it in a k'li sh'lishi either, but it is not the prevalent custom)

Can I spread mayonnaise or butter inside a boiling hot potato?

A concept, borrowed from Issur v’Heter says that a hot solid remains a k’li rishon even after being placed in a k’li sheini or sh'lishi. Accordingly, the rules of cooking in a k’li rishon apply to a potato as well. Since mayonnaise has not been cooked, it may not be put inside a hot potato. Butter on the other hand is made from pasteurized milk, which some poskim recognize as being cooked. Rav Moshe Feinstein [1] ztz”l says that one may put butter inside a hot potato, but Rav Shlomo Zalman Auerbach [2] ztz”l says that it is not permitted as butter has not been cooked in its present state.

May I sprinkle salt onto a hot potato or piece of meat?

Firstly we must differentiate between cooked salt and uncooked salt. Apparently it is becoming increasingly common to obtain uncooked salt on the US market, which complicates matters in relation to Shabbos.

As explained in last shiur, a hot solid [3] retains its heat even when placed inside a plate or bowl and consequently one may not sprinkle uncooked salt onto these items. [4] When in doubt whether the salt you have is cooked or uncooked l'chatchila one should be stringent, because sprinkling uncooked salt onto a gush (a hot solid) might result in cooking the salt. [5]

If the salt is cooked, one may sprinkle it onto a hot potato that is placed into a plate or bowl. [6]

On the exterior of an electric urn is a small transparent pipe, which gets filled with water. When opening the tap, the water in that pipe enters the urn and mixes with the boiling water, is there anything to be aware of?

The problem is that the water in the pipe is not fully cooked. Although it is close to or above yad soledes bo, it has not boiled, and by admitting the water into the urn, it will probably boil, thereby being liable for the issur of cooking. [7] There are poskim who say that it is not a problem, because the small amount of water that enters the urn is inconsequential and the way it is introduced into the urn, through a p'sik reisha or even g'rama, makes it permitted. A competent halachic authority must be asked for guidance.

If a light was unintentionally turned on in a room, may one benefit from it?

It is prohibited from the Torah to switch on a light on Shabbos due to the filament inside the light bulb. The Chazon Ish also added that one is also liable for “Boneh – constructing”. Therefore, when a light is switched on, a Torah prohibition has been transgressed, and the halacha is as follows: The Shulchan Aruch [8] prohibits deriving any benefit from an issur d'oraisso, even when performed b'shogeig (unintentionally) until after Shabbos. The Vilna Gaon, however, holds like the opinion that one may derive benefit from the issur on Shabbos itself. (This only applies to an unintentional transgression of an issur). The Mishna Berura [9] rules in accordance with the Shulchan Aruch but adds that in special cases, the lenient opinion may be relied upon.

Rav Shlomo Zalman Auerbach ztz”l held that “necessary” means that there is no other option available. In other words, it is not to be taken lightly and a Rav should be consulted!

Is there a difference between turning on a light without thinking and turning it on without noticing (i.e. by leaning on the light switch)

Without thinking is called b’shogeig – unintentional, and without noticing is called mitaseik. There is a big difference between the two. For the former one is required to bring a sacrifice (if a Torah prohibition was transgressed), for the latter there is a possibility that one is required to do teshuvah – repent.

If when walking into a room on Shabbos, one ‘forgets’ what he is doing and turns on the light, it is a shogeig, and one is required to bring a sacrifice to the Beis HaMikdash. If one leans on a wall and accidentally turns on the light, it is a misasek; some say repentance is required, although it is not the same as a shogeig.

So entering a bathroom and flicking on the light switch is shogeig, not mitaseik?

Indeed so, because if theoretically we would video a person entering a room and turning on the light and replay it in slow motion and pause just as he is about to turn on the light, we would then ask him, what are you about to do, and he would reply that he is about to turn on the light. We would then ask him whether he knew what day it was, and in shock he would invariably reply, oy vey, it's Shabbos. So it is Shabbos that has slipped from his mind, not anything else. This is called a shogeig and far more severe than mitaseik.

How does one atone nowadays for a shogeig when there is no Beis Hamikdash?

Firstly we see in the gemora that R' Yishmael inscribed in his notebook that he will bring a korban when the Beis Hamikdash will be built. Secondly, one should give tzedaka the value of a korban chatas.