The Torah teaches that, although most melachos are forbidden on Yom Tov, cooking and most other food preparation are permitted. Nevertheless, some types of food preparation are prohibited on Yom Tov, such as catching fish, picking fruit, and squeezing juice. Why are these activities different from cooking, kneading, and the other food preparatory activities that are permitted on Yom Tov?
To understand the answer to this question correctly, we must imagine ourselves preparing a meal in the days of Chazal: Refrigeration and most modern methods of preserving food do not exist, and preparing a festive meal requires baking and cooking on the day of the occasion. Although it may seem strange to us, even shechitah and soaking and salting the meat are performed the day the meal is served. Thus, the Torah permitted any activity necessary to prepare a meal that will be served on Yom Tov. It is even permitted to skin the hide off an animal that has been shechted on Yom Tov since one cannot remove the meat properly without first removing the hide.
However, some food preparatory activities are usually performed in advance of the day one intends to serve the meal. Even in earlier days, one did not begin preparing the day’s meal by catching fish. One who planned fish for dinner would catch or purchase the fish the day before, and then leave the fish in water until it was time to prepare it. Therefore, one may not fish on Yom Tov, even if one intends to fry fish for the day’s meal.
Similarly, fruits are usually picked and squeezed when they ripen, and then the juice or oil is stored. Thus, picking and squeezing fruit is not permitted on Yom Tov, even though they are steps in the preparation of food. Even picking or squeezing a small amount of fruit is prohibited, since these activities are usually performed in quantity and stored for a longer period of time.
In a like manner, the day one prepares a meal is not the time to begin grinding the wheat into flour, and it is certainly not the time to harvest the grain or to thresh it. One would grind the grain into flour at an earlier date and then store it for subsequent use. However, someone serving fresh bread or pastry prepares the dough the day the meal is to be served. Therefore, it is permitted to mix flour and water on Yom Tov. This subject leads us to a more extensive discussion about the melacha of kneading on Yom Tov.
Kneading on Yom Tov
One of the thirty-nine melachos of Shabbos is kneading, which includes any instance of combining fine particles with a liquid until they stick together. Thus, one may not mix grains or powders with liquid to create an edible cereal on Shabbos. However, since one may knead dough on Yom Tov, all kneading is permitted on Yom Tov. Thus, one may prepare oatmeal, pudding, or baby cereals on Yom Tov the same way these foods would be prepared on a weekday. (One may not mix these foods in the usual fashion on Shabbos.)
When one kneads dough on Yom Tov, the challah portion is separated (assuming that one kneaded a sufficient quantity of dough). However, one does not burn the separated challah portion on Yom Tov. Instead, one sets the portion aside to be burnt after Yom Tov (Shulchan Aruch, Orach Chayim 506:4).
If one baked before Shabbos or Yom Tov, one may not separate the challah portion on Shabbos or Yom Tov. What happens if you realize on Shabbos or Yom Tov that you forgot to separate challah? The answer to this shaylah depends on whether the dough was kneaded in Eretz Yisrael or in chutz la’aretz. If the dough was kneaded in Eretz Yisrael, then there is no solution but to leave the bread until after Shabbos or Yom Tov, and then separate the challah portion. However, if this dough was kneaded in chutz la’aretz, there is a different solution: One may eat the bread on Shabbos or Yom Tov as long as one makes sure that some of the bread remains until after Shabbos or Yom Tov. After Shabbos or Yom Tov, one separates the challah portion from the leftover bread. This separating "after the fact" is sufficient to fulfill the mitzvah of separating challah in a dough produced in chutz la’aretz (Rama 506:3). The reason for this distinction requires a bit of explanation.
Min HaTorah there is a requirement to separate challah only on dough that is made in Eretz Yisrael. (In actuality, the requirement is min hatorah only when the majority of Jews live in Eretz Yisrael.) The requirement to separate challah on dough mixed in chutz la’aretz is only out of concern that Jews living in chutz la’aretz should not forget that there is a mitzvah to separate challah. However, since the mitzvah in chutz la’aretz is only miderabbanan, Chazal allowed the leniency of separating the challah portion "after the fact" (Shulchan Aruch, Yoreh Deah 322:2-3).
Grating, Grinding, and Mashing on Yom Tov
The melacha of grinding is different from the melachos previously discussed. Some foods are ground or grated as the meal is being prepared, whereas others are ground well before the meal is prepared. For example, when preparing a kugel, the potatoes are grated as the meal is being prepared; similarly, a gourmet chef might crush fresh pepper and other spices specifically for the meal. These types of grinding are permitted on Yom Tov, as I will explain. On the other hand, one does not grind wheat the day one plans to bake bread, and it is therefore prohibited to grind flour on Yom Tov.
The laws of Yom Tov divide the various items that might be ground into four categories:
1. Items that are usually ground well in advance of preparing a meal, such as flour, may not be ground at all.
2. Items that might be ground while preparing the meal, but could have been ground earlier without affecting their flavor, such as salt, may be ground on Yom Tov, but only by grinding them in a way that is different from the usual method. For example, the Mishnah states that one may grind salt on Yom Tov with a wooden pestle rather than one of stone (Beitzah 14a). Therefore, if someone discovers on Yom Tov that he has no table salt in the house, only coarse koshering salt, he may crush the salt on Yom Tov on the table, but not with a mortar and pestle, or with a salt or pepper mill.
3. Items that taste better fresh but are usable if ground before Yom Tov may be ground or chopped on Yom Tov, but only by grinding or chopping them with a slight shinui (Rama 504:1), such as by placing a napkin on the plate or mortar on which they are being ground (Mishnah Berurah 504:19). Therefore, someone accustomed to freshly crushed pepper or spices may grind them on Yom Tov slightly differently from usual, but may not use a tabletop pepper mill.
4. Items that will become useless if ground or chopped before Yom Tov may be ground or chopped on Yom Tov in the way that they would usually be ground or chopped on a weekday. Therefore, one may mash avocado and banana, chop potatoes and onions into fine pieces, and dice salad and apples on Yom Tov the way one would on a weekday (Piskei Teshuvos 504:3).
In general, it is prohibited to measure on Yom Tov, just as it is prohibited to measure on Shabbos. Thus, one may not measure how much flour, sugar, or oil to use in a recipe (Shulchan Aruch 506:1). However, one may approximate how much flour, oil, or sugar is needed. It is permitted to use a measuring cup as long as one does not fill the cup exactly to its measuring points (Mishnah Berurah 506:3).
The Poskim dispute whether one may measure spices on Yom Tov, some permitting (even though it is prohibited to measure other items), because approximating spices may ruin the recipe if one errs (Beitzah 29a). However, Magen Avraham (504:10) contends that since most women cook without measuring spices on weekdays, but simply estimate how much they use, they may not measure spices on Yom Tov. Others contend that someone who measure spices on weekdays may measure them on Yom Tov.
Cooking that is Prohibited
One is permitted to cook and prepare food on Yom Tov only when one intends to eat that food on Yom Tov, but one may not cook for after Yom Tov or on the first day of Yom Tov for the second day. For this reason, it is important that all preparations of meals for the second night of Yom Tov wait until the first day of Yom Tov is over. Thus, there was a custom in many communities in Eastern Europe to delay the davening the second night of Yom Tov to allow sufficient time for the preparations of the night meal.
One may cook amply for the Yom Tov meal, knowing that there will certainly be leftovers that can then be served on the second day of Yom Tov. However, one may not prepare individual units of a food item, knowing that one is preparing more than can possibly be eaten on Yom Tov.
One is not permitted to cook on Yom Tov for a non-Jew, since he does not observe Yom Tov. Furthermore, Chazal forbade inviting a non-Jew for a Yom Tov meal, out of concern that one might cook special for him on Yom Tov. One may invite a non-Jew, such as domestic help, for whom you would not prepare a special dish. However, one may not cook for him on Yom Tov.
It is also forbidden to cook or do other melacha for an animal. Thus, although one is permitted to mix dry grains with liquid to create an edible cereal on Yom Tov for a person, one may not mix these items to feed a pet.
Use of Stoves and Ovens on Yom Tov
Chazal prohibited kindling a new flame on Yom Tov (Mishnah Beitzah 33a). Thus, although one may turn up an existing flame, one may not strike a match on Yom Tov (Aruch HaShulchan 502:6), nor may one light a stove or oven by using an electric igniter, since this is considered lighting with a new flame (Igros Moshe 1:115). If someone has a stove or oven that does not light with a gas pilot, it is a good idea to have a twenty-four hour candle burning over Yom Tov to facilitate lighting the stove on Yom Tov. Another advantage to igniting this candle before Yom Tov is that it enables the lighting of the Yom Tov candles on the second night of Yom Tov.
One is permitted to lower a flame in order to cook on Yom Tov. However, there are poskim who rule that one may lower a flame only when there is no option for turning up or on a different flame. According to the latter opinion, if one is cooking on a stove and one wants to lower the fire so that the food does not burn or boil out, one can do so only if there is no option for turning on another flame (Magen Avraham 514:2). However, Rav Moshe Feinstein ruled that it is permitted to lower a flame when one desires to cook with a lower flame or so that the food does not burn or boil out (Igros Moshe 1:115; 4:103).
Hashkafah of Preparing Food on Yom Tov
The Torah refers to the Yomim Tovim as moed. Just as the word ohel moed refers to the tent in the desert which served as a meeting place between Hashem and the Jewish People, so too a moed is a meeting time between Hashem and the Jewish People (Hirsch, Vayikra 23:3 and Horeb). Although on Shabbos we are to refrain from all melacha activity, on Yom Tov the Torah permitted melacha activity that enhances the celebration of the Yom Tov as a moed. Permitting the preparations of delicious, freshly prepared meals allows an even greater celebration of the festivities of the Yom Tov as we celebrate our unique relationship with Hashem.
This Shiur is published also at Rabbi Kaganof's site