The stone on my porch becomes very hot from the sun, am I permitted to warm food on it?

The halacha is that food may be warmed in direct sunlight, but is forbidden to be warmed from the sun’s derivatives. [1] Therefore it is forbidden to warm an egg by placing it on the stone, because the stone is hot from the sun. However, one may place an egg to cook in direct sunlight. This might be accomplished by cracking an egg into a white plate (that will not heat in sunlight) and placing it directly in the sunlight.

If food on the blech or hot plate is beginning to burn, may I stir the food?

This issue comes under the problem of maigis – stirring. If the food is not yet fully cooked, it is forbidden to stir the food or even to remove food from the pot with a spoon, for stirring the food further cooks the food. [2]

The poskim explain [3] that stirring is an integral part of cooking and it will cause certain portions of the food to cook, which might not have cooked without stirring.

Even if the food is fully cooked, we find that poskim [4] forbid stirring the food, especially when on the fire. [5]

So if the food is burning, all you can do is move the pot further away from the heat source, because stirring is a big problem.

If food is fully cooked, may one take food out of the pot with a spoon?

The Mishna Berura says that the Beis Yosef permits it, but many poskim say that while it is on the fire, one should not take food out of the pot with a spoon. [6] If the hot food is needed for later as well, one should remove the pot from the blech or hot plate, take food out the pot, and return it to the fire, all the while keeping the laws of chazora, namely the food is fully cooked (it must be in this situation!), the fire is covered with a blech or one uses a hotplate, one has it in mind to return and one holds onto the pot while serving the food. The Chazon Ish, however, held that when fully cooked, it is permitted to take food out with a spoon even when on the fire (taking care not to stir the food). In a case when the food is needed for later, and if removed from the fire it cannot be put back (because it is not on a blech or hot plate), there is room to be lenient and remove food from the pot while it is still on the fire. (Sh’miras Shabbos Kehilchasa 1-32).

 Is there a difference between stirring food when it is on the fire and when it is off the fire?

If the food is not yet fully cooked, even when it is off the fire it may not be stirred. If fully cooked, the Mishna Berura (318:116) says that it is permitted to stir (off the fire). However due to the stringency of the Rama (who says that one should not insert a spoon into a pot at all, rather one should spill the contents into a bowl), the M"B says (318:117) that there is room for stringency with regards to stirring, but as for taking food out with a spoon, there is no problem.

May one sprinkle sea salt into hot soup?

Before one can answer this question, one has to know whether the particular salt in question was manufactured through sun evaporation, which is not considered cooked, or through a cooking process.

The Mechaber holds that one may add uncooked salt to a k’li rishon that is off the fire, and all the more so into a k’li sheini, but the Kaf HaChaim (318:106) writes that one who is stringent, merits a blessing.

The Rama holds that one should not add salt even into a k’li sheini. However the Mishna Berura (318:71) writes that if the salt is precooked, it may be added to a k’li sheini, but one should refrain from adding it to a k’li rishon. The reason for this stringency (even though salt is cooked) is because it dissolves and resembles a liquid, and with regards to liquids we say that one may not re-cook a cold liquid in a k'li rishon, even off the fire.

So bottom line is that if the salt is precooked it may be added to a k'li sheini but if not cooked, it may only be sprinkled into a k'li sh'lishi.

Muktze

If oil is dripping from an oil lamp, is one permitted to place a plate beneath the lamp to catch the dripping oil?

This involves a concept called ‘mevatel k’li meheichano’, which means that one is forbidden to cause a utensil to become muktze. By doing so, Rashi [7] says that it is as if one has cemented the utensil in its place, and is similar to the melacha of Boneh.

Since the oil is muktze, when the oil drips into the utensil the utensil becomes muktze, and it is as if he has cemented it in its place. [8]