Stirring the pot, Part I

Hi,

Stirring a pot of fully cooked food, which is atop a heating element, is prohibited rabbinically on Shabbat. Although it is biblically permitted, the Sages forbade it lest one think the food is cooked when it is not, and so violate a biblical law.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 4:74:Bishul 8)

Have a great day,
Mordechai