604. Food That Was Removed from the Fire

Shabbos 3:10

In a case where it is permitted to leave food on the fire, if it was removed from the fire on Shabbos, it is prohibited to return it to the fire. Food may only be returned to a stovetop from which the coals have been removed or covered, or that was heated with straw or stubble as fuel. [All of this is a preventive measure against coming to stoke the coals.] This is only permitted if the food was not set down after being removed. If it was set down, it may not be returned even to a stovetop whose coals were removed or covered. Similarly, food may not be returned to an oven that was heated with olive refuse or wood even if one removes or covers the coals because they are very hot. Whenever food may not be returned to the fire, it may likewise not be placed next to the fire to keep it warm.

Shabbos 3:11

One may not stick a ladle into a pot in order to remove food while it is still on the fire on Shabbos because doing so stirs the pot. Stirring is one of the activities of the labor of cooking, and is therefore prohibited on Shabbos. One may move a pot from one stovetop to another even if the first is not as hot as the second but one may not take food on a stovetop and cover it to retain its heat or take food that was covered to retain its heat and put it on the stovetop.