Recently at a person’s house, we were confronted with a fascinating halachic question as to whether one may put a topping such as ketchup onto a piece of hot meat or potato on Shabbat. This question is interesting because it highlights two fundamental laws that we have discussed in previous article.
1) The Concept of “Gush”: The Maharshal suggests that a dry piece of solids never looses its status of being considered Kli Rishon (first vessel), as long as it is above Yad Soledet Bo (around forty-three degrees Celsius). This means, according to him, that the potential leniencies of kli Sheni and kli Shelishi (of second and third vessels), do not apply to dry solids. Hence, a hot piece of potato has the ability to cook even on a serving plate.
2) Reheating Liquids: We have already discussed that there is a fundamental argument amongst the greatest medieval commentators as to whether one may reheat liquids that have been previously cooked on Shabbat. The Shulchan Aruch’s view is that of Rashi and his school and holds that scripturally one is prohibited from doing so. The Rema suggests differently and holds primarily like the Rambam that one may reheat liquids but offers a stringency of custom that this should only apply to liquids that remain at least lukewarm from the original cooking.
The question therefore arises, may I place ketchup, which is a pre-cooked liquid on a dry solid (gush) such as a potato.
3) The Poskim: Rav Moshe Feinstein (Igrot Moshe, Ohr Hachaim, 4; 74), posits that one may indeed be lenient in our case. The reason for this is because in both these issues (gush and reheating liquids), the letter of the law is to be lenient but in practice we are stringent out of custom. As a result, there is no reason to take on both stringencies simultaneously. That is to say, customarily we do not reheat liquids and we are particular about the powers of gush to cook but when both issues arise in the same instance, there is no need to be stringent as this would be a double stringency.
4) Concerning Butter: Butter, however, might not enter into this category of leniency ant it is questionable as to whether butter on a hot potato. This is because it is unclear at what temperature the butter was pasteurized. Only if it were pasteurized above seventy-five degrees Celsius, would it be permitted on a hot potato. Less than this temperature, a question would remain.