The holiday of Shavuot will be celebrated, G-d willing, in approximately a week and a half on Wednesday, the 6th of Sivan (and outside of Israel on Thursday, the 7th of Sivan as well). Let us, therefore, begin to discuss some of the pertinent laws of the holiday.
The Torah states (Shemot 12) regarding the various holidays, i.e. the first day of Sukkot, Shemini Atzeret, the first and last days of Pesach, and the holiday of Shavuot: “No work shall be performed on them; however, any (work necessary for) food preparation eaten by all, this alone may be performed by you.” This means that any work which is forbidden on Shabbat is also forbidden on Yom Tov, besides for work needed to prepare food which is permissible on Yom Tov.
Some works pertaining to the Yom Tov food preparation which the Torah allows on the holiday itself include cooking, frying, baking, and the like, as we shall soon discuss.
The Sefer Ha’Chinuch explains that the reason the Torah forbade performing work on holidays is in order for the Jewish nation to remember the great miracles that Hashem performed for them and their ancestors and to pass this message on to their children. If work was permissible on these days, the honor of the festival and joy of the holiday would be forgotten because everyone would be busy at work; thus, due to the prohibition of working on the holidays, the Jewish people will be free to gather in synagogues and Batei Midrash to hear words of Torah and wisdom from luminaries of the generation who expound Halacha and stories of the Torah. This is based on the teaching of our Sages, “Moshe instituted that the Jewish nation expound the laws of Pesach on Pesach, the laws of Shavuot on Shavuot, and the laws of Sukkot on Sukkot, as the verse states, ‘And Moshe spoke out the festivals of Hashem to the Children of Israel.’” Similarly, our Sages taught, “Shabbat and holidays were only given to the Jewish nation so that they may delve in Torah study.” We were therefore commanded to have a complete cessation of work, excluding work needed for food preparation (for instance, preparing a dish for a holiday meal, according to the conditions and procedures we shall lay out in following Halachot). Similarly, our Sages have taught, “There is no distinction between Shabbat and Yom Tov besides for [the prohibition of] food preparation.” Nevertheless, one should divide the hours of the holiday with half being spent in the synagogue and Bet Midrash and half being spent eating, drinking, and enjoying the holiday.
Although the Torah permits performing work connected with food preparation (for a Jew), there are, nevertheless, some forms of work that our Sages have forbidden although they may be associated with food preparation.
Our Sages prohibited one from harvesting his field or vineyard on Yom Tov, even if this is for the purpose of food preparation (for instance, if one would like to pick an apple from a tree in order to eat it on Yom Tov), for fields and vineyards are usually harvested all at once, thus causing one to be busy at work all day long; this will, in turn, prevent one from enjoying the holiday. The same prohibition applies to collecting scattered stalks, threshing grains, squeezing fruits, selecting (separating different species from one another), grinding, and sifting.
Some say that performing these works on Yom Tov is actually a Torah prohibition. Our Sages in the Talmud Yerushalmi actually base the prohibition to perform these works on certain verses, as the Torah states, “However, any (work necessary for) food preparation eaten by all, this alone may be performed by you,” immediately followed by the verse, “And you shall guard the Matzot.” This means to teach us that works associated with food preparation are permissible only from “guarding” and on, meaning from the kneading of the dough and on (for when flour comes in contact with water its tendency is to leaven unless certain “guarding” procedures, which are used for Matzah baking, are implemented). Thus, works preceding kneading are prohibited on Yom Tov, whereas works performed after kneading are permitted on Yom Tov.
Thus, although kneading dough is prohibited on Shabbat, it is indeed permissible on Yom Tov. The same applies to cooking, frying, and the like, as we shall soon explain.