The laws of Borer on Yom Tov slightly differ from Shabbos; at times it retains the Shabbos restrictions while at others it receives a new set of laws relating to its form of separation. The following is the general rule:

Foods that are sifted many days prior to use:^[1] Those foods of which it is common to separate their waste many days in advance, and hence have the food placed in storage for future use, such as grains, retain the same Borer restrictions as Shabbos, and hence one may only remove the good from the bad with one’s hands for the sake of right away use.

Foods that are separated for that day’s use:^[2] Those foods of which it is common to separate their waste on the day of their use, then if one could have separated the waste before Yom Tov, they retain the same Borer restrictions as Shabbos.^[3] If however one was unable to separate the waste before Yom Tov, then one is to separate the waste and food in the method that will be least strenuous. If there is more food than waste and it is easier to remove the waste, then one is to remove the waste. However, if there is more waste than food, then one is to remove the food, even if it is more troublesome to do so.^[4] In the above case that one was unable to separate the waste before Yom Tov, it is permitted to separate in the above mentioned method even through using a vessel and even for non-immediate use, so long as it is done for the sake of eating on Yom Tov.^[5]However one may not use professional Borer vessels such as a sieve and sifter, [that are used for separation of many days’ worth of foods^[6]].^[7] It is likewise forbidden to soak the food in water and have the waste float up or sink to the bottom.^[8]

Sifting flour:[9] Sifting is one of the prohibited Melachos on Yom Tov even when done for the sake of food and hence it is forbidden for one to sift flour for the first time on Yom Tov. It is forbidden to do so even with an irregularity, and even if one did not have the ability to do so before Yom Tov. However, if the flour was already sifted before Yom Tov, then it is permitted to re-sift it on Yom Tov using a slight irregularity, such as to do the sifting directly over the table rather than over a plate, or through a different irregularity than what one is used to doing during the week. [Today’s flour is already pre-sifted in the factory and hence may be resifted on Yom Tov for the sake of checking for insects, although if it could have been done before Yom Tov then one is to do so with a Shinuiy.^[10]]

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[1] Admur 506:4; 510:3

[2] Admur 510:3-5

[3] Admur 510:5

[4] Admur 510:4; Unlike Nitei Gavriel 5:7

[5] Admur 510:3; Nitei Gavriel 5:9; Piskeiy Teshuvos 510:1

[6] So explains Admur in 510:2; Piskiey Teshuvos 504:1; Nitei Gavriel 5:6

[7] Admur 510:6

[8] Admur 510:6; Piskeiy Teshuvos 506:3; See however there footnote 14; SSH”K 11 footnote 20

[9] Admur 506:3

[10] Beir Moshe 8:204; Piskeiy Teshuvos 506:4

[11] Piskeiy Teshuvos ibid

[12] Cheshev Haeifod 3:35; Piskeiy Teshuvah ibid; Nitei Gavriel 5:22

[13] Admur Kuntrus Achron 510:4; Nitei Gavriel 5:22

Other opinions: Some Poskim are stringent in this matter just like on Shabbos. [P”M 506 M”Z 3; M”B 506:12; Kaf Hachaim 506:14]

[14] Based on Admur 510:3; Nitei Gavriel 5

Other opinions: Some Poskim rule one may never remove the fy from the cup, and is rather to follow the law on Shabbos. [M”B 506:12]

[15] Nitei Gavriel 5:27 in name of Ketzos Hashulchan 146 footnote 35 [however he does not write that there]

[16] Ramach; Beis Yehuda 2:46; Birkeiy Yosef 495:3; Kaf Hachaim 495:11

[17] The reason: As it is not possible to make it with a Shinuiy on Yom Tov, as well as that it is Uvdin Dechol. [Poskim ibid]

[18] Piskiey Teshuvos 504:3; Nitei Gavriel 5:14 based on Admur 510:6