Eruv Tavshilin

If Yom Tov falls out on Friday (or on Thursday and Friday outside Israel), in general, one may not cook or bake from Yom Tov for Shabbat, however, if one cooked and there was leftovers it may be eaten on Shabbat. Yet, if one designated an Eruv Tavshilin from before Yom Tov then it’s permissible to cook or bake from Yom Tov for Shabbat.

Procedure and text

1. One should hold the cooked and baked foods in one's right hand as one says the Bracha and Erev stipulation.
2. The text of the Bracha for Erev Tavshilin is: ברוך אתה ה' אלוקינו מלך העולם אשר קדשנו במצותיו וצונו על מצות עירוב. Then one should make the following stipulation: בדין יהא שרי לן לאפויי ולבשולי ולאטמוני ולאדלוקי שרגא ולמעבד כל צרכנא מיום טוב לשבת , meaning, "With this Eruv it should be permitted for us to bake, cook, insulate food, light a candle, and do any need from Yom Tov for Shabbat". One must understand what one is saying and if one doesn't understand the Aramaic one should say it in a language one understands.

What foods should be used for Erev Tavshilin?

1. A baked item such as bread and a cooked dish should be used for the Eruv Tavshilin. The cooked dish must be something which is usually eaten with bread such as a piece of meat, fish, or eggs.
2. If one made the Erev Tavshilin only using one cooked dish, after the fact it’s permissible.
3. If one made the Erev Tavshilin only using one baked item, like bread, this isn’t considered a proper Erev.
4. If one is only going to cook and not bake then one only needs one cooked dish.

Size of Erev Tavshilin

1. The one baked dish and one cooked dish must be the size of a Kezayit and it’s preferable to use a whole loaf of bread and significant piece of meat or fish.

After making Erev Tavshilin, what are the laws of cooking on Yom Tov

1. Erev Tavshilin only permits one to cook on Friday however, if the first day of Yom Tov is on Thursday and the second one on Friday one may not cook from Thursday for Shabbat.
2. One should prepare the food on Yom Tov for Shabbat earlier in the day so that it will complete cooking well before Shabbat so that it’s possible it could have been used on Yom Tov. If it turns out that there’s not enough time to complete the cooking until right before Shabbat, if it’s Yom Tov Sheni one may be lenient, but if it’s the first day of Yom Tov then one shouldn’t be lenient unless it’s a time of great need. However, some defend the practice to permit cooking until sunset of Friday.

Eating the Erev Tavshilin

1. Some have the minhag to eat the Erev Tavshilin for Seudat Shelishit.
2. If the Erev is eaten or lost one may not continue to cook on Yom Tov in preparation of Shabbat.

If one forgot to make Erev Tavshilin

1. There’s a mitzvah to make an Erev Tavshilin upon each individual and also upon the leader or Rabbi of the city.
2. If one forgot, was unable, or didn’t know how to make Erev tavshilin, the first time one may rely on the Erev Tavshilin of the Rabbi of the town. However, if one had the ability but wanted to rely on the Rabbi of the town or if he forgot twice, he may not rely on the Rabbi’s Erev.
3. If one didn’t make Erev Tavshilin according to some poskim one may not light Shabbat candles on Yom Tov which falls out on Friday. Therefore, in such a case one should give the candles to another Jew and let them light for him or only light one candle.
4. If Yom Tov (excluding the two days of Rosh Hashana) falls out on Thursday and Friday, and one forgot to make Erev Tavshilin before yom Tov one may make Erev Tavshilin on the first day and stipulate “If today is Yom Tov then there’s no need for an erev and if today isn’t Yom Tov then the erev should be set aside in order to permit cooking and baking.”
5. Some say that it’s preferable to make such a stipulation while others say that in such a case it’s better to rely on the Erev of the Rabbi of the town.