In the previous Halachot, we have discussed some issues related to the forbidden work of selecting on Shabbat. We have also mentioned that it is only permissible to select on Shabbat when three conditions are met: One must select by hand and not with the use of a utensil (such as a strainer), one must select the food from the waste and not the opposite, and one must do so in order to eat the food immediately (and not to leave it for a later time).
In the previous Halacha we have mentioned the opinion of several Rishonim that one may remove the forbidden fat (whose consumption is subject to a Torah prohibition and must thus be removed) from the meat which it is attached to on Yom Tov. We have explained that the reason for this is because this is similar to peeling the peel off of a fruit which is not included in the forbidden work of selecting on Shabbat.
Similarly, the Rama in his notation on the Shulchan Aruch (Chapter 321) rules that one may peel an onion or garlic on Shabbat, for although by doing so one is separating waste from food, nevertheless, this is not prohibited since this is not being done in a “selecting manner,” rather this is being done in an “eating manner.” However, even regarding peeling onion or garlic, this may only be done when it will be eaten immediately. For instance, if a woman peels garlic and cuts it and mixes it into a salad, and everyone immediately sits down to eat it during the meal, this is indeed permissible. However, to peel garlic in order to use it after a half-hour’s time is forbidden.
Based on this we can infer that although peeling eggs on Shabbat is not prohibited as this is similar to peeling a fruit; nevertheless, it will be prohibited unless one has in mind to eat it immediately. However, if one intends to eat it after a half-hour’s time or later, one may not peel them on Shabbat.
Nevertheless, this applies only to onions, garlic, or eggs whose peel is not actually attached to the edible item and it only serves to “wrap” it; however, regarding apples whose peel is actually stuck to them tightly, Maran zt”l writes that such peeling cannot be considered selecting and it is thus permissible to peel apples even if one only intends to eat them in an hour or so, since the rules of the forbidden work of selecting do not apply here. (This is especially true since the peel of the apple is edible in and of itself and cannot be considered actual “waste”; thus, even according to the more stringent opinions, there is no Torah prohibition applicable here and one may be lenient regarding this matter.)
Summary: A food, such as an onion, garlic, or egg, which is surrounded all around by a peel, may be peeled on Shabbat as long as this is being done in order to eat the food immediately. However, it is forbidden to do so if one intends to partake of this food only in a half-hour’s time (unless this is being done close to the beginning of a meal, in which case it should be peeled close to the start of the meal, even if the food will only be eaten after a half-hour).
A fruit whose peel is stuck to it tightly and is edible on its own, such as an apple, may be peeled on Shabbat even if one intends to eat it a long time later, for since the peel is stuck to the fruit tightly, it is considered like one is slicing the fruit in two and cannot be considered “selecting.” Maran Harav zt”l rules that one may even peel an apple using a special peeler which is designated for this purpose.