By Rabbi Dovid Ostroff
What is the halacha with regards to immersing kishke inside cholent?
In previous shiurim we dealt with the two types of hatmana (storing) – hatmana that adds heat and hatmana that does not add heat. The former is prohibited even before Shabbos and the latter is prohibited on Shabbos.
Many are accustomed to placing kishke wrapped in plastic film or aluminum foil inside a cholent and the issue of hatmana arises. Since heat is constantly added to the kishke it would seem to be prohibited even before Shabbos. What is the heter?
- Hagaon Rav Shlomo Zalman Auerbach ztz”l explained that it is not considered hatmana.  The essence of hatmana is to prevent heat loss but in this case it is not applicable. The kishke and cholent receive direct heat from the hotplate or fire and the cholent (which would be the matmin – the wrapper) is not needed to add heat to the kishke.
- Rav Eliyahu Falk shlita says that the problem exists when the kishke is wrapped in two covers but if wrapped in a single sheet of foil it is permitted. 
- Make holes in the wrapper surrounding the kishke or do not allow the kishke to be totally submerged inside the cholent. 
May I put soup nuts into my soup?
To answer this we must familiarize ourselves with the concepts ein bishul achar bishul and yeish bishul achar afiya.
A fully cooked solid item is not subject to the restrictions of cooking and if certain conditions are complied with it may be reheated.
How do we know this?
The Mishna in Shabbos 145b says “anything placed in hot water before Shabbos may be immersed in hot water on Shabbos”. The Tosefos  explains that the word ‘placed’ in the Mishna means ‘cooked’, i.e. something cooked before Shabbos may be reheated on Shabbos. The Shulchan Aruch  cited this halacha but altered the word ‘placed’ in accordance with Tosefos and wrote “a dry item fully cooked before Shabbos may be immersed in hot water on Shabbos”. 
Why may one only reheat solids and not liquids?
The gemora in Shabbos 34a  states that one may not wrap (hatmana) an item on Shabbos lest one finds it cold and reheats it, which would lead to the violation of cooking on Shabbos (Rashi).
The Tur was perturbed by this apparent contradiction to the Mishna cited above, which says that one may reheat a cooked item. He therefore explains that the Mishna refers to solid items and the gemora to items with liquid, such as meat with gravy or soup.
Conclusion – solid, dry items that are fully cooked such as schnitzels, kugel, chicken and meat may be reheated on Shabbos. Items containing liquid such as meat with gravy or soup may not be reheated on Shabbos. 
How is one to reheat solid cooked items?
It is crucial to note that two issues are involved in reheating. The first applies to the items being reheated, which is dealt with above. The second is the manner used to reheat.
We have previously learned that one may not place anything directly onto a heat source on Shabbos because it appears as if one is cooking. Consequently, food may not be placed directly onto a blech or hotplate  and definitely even more so, not placed onto an open flame – electric or gas.
The preferred method is to place food onto a pot already on a heat source, such as a gas range, electric range, hotplate or blech. One may also place it on an electric urn.
How dry must a solid be to be called dry?
A moist solid (although slightly wet) may be reheated because moisture is of no significance.  Rav Shlomo Zalman Auerbach ztz”l permits reheating kugel even though it is moist with oil.
So what’s with the soup nuts?
Soup nuts (as opposed to croutons) are deep fried in oil and as such one may reheat them on Shabbos. Consequently, placing them into hot soup on Shabbos is permitted.
 Tikunim umiluim chapter 42 footnote 242.
 The first wrapping is the natural container, which is not hatmana and the second the storing – hatmana. A single sheet wrapped around a few times is permitted.
 See the SS”K 42:63 and footnote 242, but see the relevant tikunim.
 Shabbos 39a ã”ä ëì.
 Simon 318:4.
 See the Beis Yosef simon 318:4.
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 Certain clauses must be added, which we will be”H deal with later.
 Rav Moshe Feinstein writes that one may place warm food directly onto a hotplate that cannot cook. Common hotplates are hot enough to cook and therefore one must ask one’s rav whether one may place food directly onto a hotplate. Certain Sephardic rabbonim permit placing cooked food directly onto a hotplate on Shabbos and once again one must ask one’s rav.
 HaRav Sternbuch shlita. The Shulchan Aruch HaRav simon 318:11 writes ‘a dry item that is totally void of liquid’ may be reheated. With respect to tea leaves boiled before Shabbos, the Mishna Berura writes that one must pour the essence from the leaves and they should be dry. Theirs is a stricter view.