It was over 40 years ago at a period where there was communal kitchen at the kollel where I was studying at. On an occasion when Yom Tov was on Friday, the women in the kitchen, who were kollel wives, themselves decided that they they had to wait till Shabbos began to wash up the dishes from the Friday Yom-Tov meal. Their reasoning was that since one was allowed to wash up dishes on Shabbos, this was not covered by Eruv Tavshilin.  The women in fact had support for their actions – the Mishnah Berurah! There it states that Eruv Tavshilin only permits things which are “tzorchei seudah”. (Mishnah Berurah 528:3) It should be mentioned however that the custom is to allow things such as hachanah, which would include washing up the dishes on Yom Tov for Shabbos.

The norm is make eiruv tavshilin using meat, fish or an egg. But one is by no means limited to these foods. According the Gemara (Beitzah 16a) and it is brought in the Shulchan Aruch (Orach Chaim 527:6), one can even use the fat scraped from a knife. So in the days before having to make an eiruv tavshilin, scrape off the fat from a knife until you have an accumulated amount of fat which is the size of a kezayis! However, needless to add, it is more respectable for this mitzvah to use meat, fish or an egg!

When making eiruv tavshilin, one makes the declaration “bahadein eiruva yehey ...”. The language of this declaration is Aramaic, because that was the language people then spoke, and it is essential that those making this declaration in eiruv tavshilin understand what it means. (Mishnah Berurah, Sha’ar Hatziun, 529:55) In practice, however, probably the majority of people have no idea what it means! The following suggestion would surely help solve this problem for one who is using a siddur with the translation on the opposite page. In all siddurim, the translation (for example: English) of this declaration appears, as with all the prayers, on the English translation side of the siddur, and therefore a person using such a siddur will not  take any particular notice of the translation of this declaration. Let this declaration appear in English on the same side as the Hebrew text, directly under the declaration in Aramaic, with a note in English stating that the person should read it in English.  (A similar thing can be done with the declaration following bedikas chometz.)