Q. I recently heard in Rav Miller’s name that there is no איסור הגסה (prohibition of stirring) in a crock pot even before removing the insert as long as the food is (completely cooked) מבושל כל צרכו. I found this quite surprising, is this accurate?

A. Mishna Berura (318: 113) quotes Beis Yosef who permits extracting well cooked food from a pot still on the fire, although Eliahu Rabba is stringent. In regards to stirring he quotes in n. 118 and in Sharei Tzion (ibid. 136) the Kol Bo that thorough mixing of well cooked food is prohibited when the pot is still on the fire. However, Chazon Ish (Shabbos 37: 15) permits when the fire was left uncovered and therefore the pot cannot be removed, since one will not be able to return it to the fire. Igrois Moshe (O.H. 4: 74: 9) is stringent even in regards to stirring a heavy pot that cannot be easily removed from the fire. The reason quoted is that there may be left small still uncooked pieces in the pot.
In regards to a crock pot, Thirty Nine Melochos (2: p. 646) permits extracting from it when left without separation of the insert, as one would not be able to return it to the crock pot.

Horav Shlomo Miller’s Shlit”a opinion is that when the food is already well cooked, even when the pot is still on the fire, non-extraction constitutes a distant stringency since stirring crock pots is not a common way of cooking and the presence of small still uncooked pieces is unusual. Therefore one may extract food from the crock pot itself and when needed for food removal, perform also light stirring.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a