Must one always use a hotplate or blech?

As mentioned in the previous shiur, Chazal were concerned that one might stoke the coals on Shabbos in order to heat the food. They thus devised a method whereby people would be deterred from doing so, which nowadays is either by placing a blech (a cover) over the flames or by using a Shabbos hotplate. [1]

Hypothetically, if one would not stoke coals for certain foods or beverages, it is superfluous to place a blech on the flames.

Which foods would not need a blech or hotplate?

All opinions agree that food that is fully cooked and 'mitztamek v'ra lo', which means that it is ‘hardening to its detriment’, may be left on an open flame and does not require a blech. [2] The classic example is hot water. Fully cooked hot water does not cook any more when left on or near a heat source - it merely remains hot. By raising heat one will hasten evaporation, which is not usually desired. Consequently, Chazal did not deem it necessary in such a case to modify a heat source as one would not want to raise the heat and lose the water.

Meatloaf is another example. [3] After a certain point it contracts and dries up and again one would not raise the heat.

Practically this means that one would be permitted to leave a pot of fully cooked meatloaf and water on an open flame before Shabbos, without having to keep it on a blech or hotplate.

How do you define a cooked cholent?

A fully cooked cholent is different and usually defined as 'mitztamek v'yafeh lo', i.e. the more it contracts the better it tastes.

Does that mean that one may not leave cooked cholent on an open flame?

Food fully cooked that improves when left on a heat source is subject to a very famous machlokes (halachic argument). [4]

Chanania holds that food cooked to the degree of ma’achal ben Derosai (food eaten by an infamous thief called ben Derosai) may be left on an unmodified heat source. Ben Derosai would not fully cook his food, because he was always on the run from the law. Chanania ruled that since food cooked to that degree is edible, there is no room to be concerned that one would stoke coals in order to hasten cooking.

Chachamim argue with Chanania and hold that unless food is fully cooked and hardening to its detriment it may not be left on an unmodified flame, which means that a blech or hotplate is required.

How much is ma’achal ben Derosai?

Rashi holds that it is food ¹/₃ cooked and the Rambam holds that it is ½ cooked. Halacha is according to the Rambam. [5]

Is the halacha according to Chanania or Chachamim?

The Shulchan Aruch [6] rules in accordance with Chachamim and thus Sephardim are required to use a blech or hotplate, unless the food is fully cooked and îöèî÷ åøò ìå.

The Rama’s opinion [7] is complicated. The Rama rules like Chanania but we find a machlokes between the Mishna Berura and the Chazon Ish.

The Mishna Berura [8] explains that the Rama means that one may only rely on Chanania when necessary, such as when unexpected guests arrive and food will not be fully cooked by the time Shabbos arrives. Ordinarily one must conduct oneself according to Chachamim, which means that a blech or hotplate must be used as most foods are not îöèî÷ åøò ìå.

The Chazon Ish [9] interprets the Rama saying that one may l’chatchila act in accordance with Chanania.

Contemporary poskim rule that that for most foods a blech or hotplate must be used, which follows the Mishna Berura. However, when no blech is available and the food is half cooked, one may rely on the Chazon Ish and use the stove without a blech.

There are many other reasons to use a blech and hotplate, as will be explained be”H in future shiurim.

What should one do when a blech or hotplate is not available?

Sephardim, who follow the rulings of the Shulchan Aruch, have a bigger problem, because only foods fully cooked and îöèî÷ åøò ìå may be left on an open flame. There is another innovation that can be used in such a case, which we will discuss another time.

Ashkenazim have it easier in this case and may rely on Chanania, i.e. food half cooked may be left on an unmodified heat source.

Seeing that these halachos are fairly complicated, whenever one deviates from the norm (of placing food on a blech or hotplate), one should consult one’s rav as to the correct procedure.