As we have learned, if food is not adequately cooked (whichever definition of “adequately,” as defined in the previous section, is adopted), one may not leave it on the fire before Shabbat begins, because one may come to turn up the flame on Shabbat. However, one may do so if the flame is covered. Covering the flame, thus reducing its heat, serves as a reminder not to raise the flame later. Furthermore, were one to forget and go to turn up the flame, he would see that the fire is covered and remember that this is forbidden, and thus refrain from proceeding. Therefore one may leave foods that are not adequately cooked on an electric plata, since its heating elements are covered.
One may also cover the fire by placing a blekh (metal sheet) over the burners and leaving adequately cooked foods on it, since covering the fire is a clear indication and reminder that it is Shabbat, effectively preventing one from forgetting and turning up the flame. Ideally, it is also recommended to cover the knobs that control the flames of the burners.
Although one may put foods on a blekh or plata even if they are not fully cooked, le-khatĥila it is better that all the foods be fully cooked before Shabbat begins. As long as they are not fully cooked, any action that will make them cook faster is prohibited by Torah law. For example, if one removed the cover on a pot containing food that is not fully cooked, one may not replace the cover. Similarly, one may not move the pot to a hotter place on the plata (as explained in section 3). Therefore, it is preferable to leave only fully cooked foods on a plata (SSK 1:72).