Borer-Separating big pieces from small pieces in a salad on Shabbos:
- Example: Mommy asked two of her daughters to cut up vegetables for the salad for the Shabbos meal. Each daughter cut the vegetables in a different size with one set being much larger than the other, and entered them in the same salad bowl. The mother feels that this is not befitting to put on the table and therefore desires to separate the large cut vegetables from the small cut vegetables and serve them both in two different serving bowls. The question is raised as to whether this separation of the sizes of vegetables is subject to the Borer restrictions or not.
It is Biblically forbidden to separate one species from other species on Shabbos without fulfilling the three Borer conditions which allow it to be done, which include 1) separating the good from the bad [i.e. what you want from what you don’t want], 2) using your hands, 3) for the sake of right away use. The emphasis of this restriction however is specifically on the separation of species from one another, as opposed to the separation of sizes of the same species, or the same mixture of species, as will now be explained next.
B. The law:
It is permitted on Shabbos for one to separate different sizes of the same species of food from each other without following the Borer restrictions and conditions. Thus, for example, if a tomato was caught in both small and big pieces it is permitted for one to separate the big pieces from the small pieces without any restriction, in any order he sees fit, and even to use later on in the day. Furthermore, if a number of different vegetables were cut in both big and small pieces [i.e. cucumber, tomato’s, etc], it is permitted for one to separate all the big pieces of all the vegetables from all the small pieces of all the vegetables without any restriction, and in any order one sees fit, and even for use later on in the day. Thus, in the example above, it is permitted for the mother to separate the big vegetables pieces from the small vegetable pieces in the salad bowl any time she sees fit, even much time before the meal, and it is not subject to the prohibition of Borer. This allowance however only applies if indeed there is no separation of species taking place but just of sizes. If, however, the large pieces are one species and the small one is a different species, then this is considered a separation of species and not just of sizes and would be subject to all the Biblical Borer restrictions. Thus, for example, if a tomato salad was cut up using both regular tomatoes and cherry tomatoes and one desires to separate the small pieces of cherry tomatoes from the regular tomatoes, then since these two tomatoes are defined as two different species their separation would be subject to the Borer prohibition and be restricted to its permitted conditions of separation.
 Admur 319:1
 Admur ibid; Michaber 319:4
 Admur ibid; Michaber 319:1
 Admur 319:2; Michaber 319:2
 Admur 319:6 “There is only a prohibition of separating when one separates waste [i.e. inedible parts] from the food or vice versa. However, if one separates food from food [of the same species], even if he utterly only wishes to eat one of them while the second one he wants to take and throw out, [nevertheless this unwanted food] is not considered waste due to this since it is [nevertheless] fit to be eaten. Therefore, it is allowed to separate it from the food which one wishes to eat and doing so does not contain [the prohibition] of separating waste from food. As long as [the mixture] is of a single species, then even though one separates large pieces from small pieces [nevertheless] this is not [Halachically] considered separating at all being that the entire [mixture] is fit to be eaten, and there is thus no waste [in the mixture]. [It is therefore] allowed to separate from it in any way that he wishes and even in order to eat it later on that day [meaning while it is still Shabbos]. If the [mixture] contains two different species and one [wishes to] separate from amongst both of them together the large pieces from the small pieces, then it is allowed since one is not separating one species from another.”; Rama 319:3; Terumos Hadeshen 57
Other opinions: Some Poskim rule that on the contrary, the prohibition of Borer applies even by a mixture of the same species of food, as in such a case the separation is even more recognizable, and hence it remains Biblically forbidden to separate large pieces from small pieces even within the same species. [Taz 319:2 “Since there is a Chashash of a Biblical prohibition, therefore one should be stringent even by one species and not separate even in a single species the large pieces from the small pieces”; Opinion of Gadol brought in Terumas Hadeshen ibid; Implication of Maharil Hilchos Pesach p. 170 regarding big and small Matzah crumbs; Implication of Rashal in Yam Shel Shlomo Beitza 1;] Practically we do not rule like this opinion. [All Achronim ibid negate opinion of Taz ibid; M”B 319:15; omitted in Admur ibid] Some Poskim, however, conclude that it is proper to be stringent even by a single species. [Chayeh Adam 16:5, brought in conclusion of Kaf Hachaim ibid]