How to Mix in a Crisscross Motion [שתי וערב]
10. Using a crisscross motion to mix as a shinui in the mixing is mentioned multiple times in these halachos. The way to do this is by putting a spoon into a mixture, e.g., eggs and oil, and moving it away from oneself and back toward oneself, even going back and forth multiple times (כדעת הרי''ף והרמב''ם הובא בב''י סי' שכ''ד ד''ה ומ''ש רבינו ). The spoon may also be moved a drop to the sides as long as it is a back-and-forth motion. Then, the spoon is taken out of the mixture, placed back in, and moved to the right and left multiple times (חזו''א סי' נ''ח סק''ו, שו''ת אג''מ ח''ד סי' ע''ד לש אות י' ).
11. If one does not want to take out the spoon before switching directions, he can bring the spoon to the middle of the dish and then change direction.
12. It is also considered a crisscross motion if one moves the spoon back and forth in the same direction the entire time and periodically rotates the dish a quarter turn since effectively, the same thing happens.
Shinui in Adding the Water
13. If, during the week, one usually puts in the dry ingredient first and then the liquid, and that is what most people commonly do today, it is a shinui on Shabbos to change the order and put the liquid in first and then the dry ingredient (שו''ע סי' שכ''א סי''ד ).
14. If, during the week, one puts the liquid in first, he should change the order on Shabbos and put in the dry ingredient first and then the liquid. One must be careful to pour all the liquid in one stream; if he first puts in just a bit, it becomes a thick mixture, and then he violates the issur d’oraisa of just adding water according to some poskim (חזו''א סי' נ''ח סק''ח ד''ה הא ).
15. No set order. Some hold if there is no set order during the week, i.e., sometimes one puts the dry ingredient in first and other times the liquid first, he can still be meikel if he will put in the dry ingredient first and then the liquid, as that is mentioned in the Gemara (תרומת הדשן סי' נ''ג, א''ר הובא במ''ב סקנ''ז ).
16. Others hold there is no heter to make the mixture with a shinui in such a case, as there is no way to change from the way it is normally prepared during the week (ט''ז סקי''א, חזו''א סי' נ''ח סק''ה ד''ה ולדעת ). Nevertheless, one can be meikel in a situation of necessity by doing a shinui in the mixing (חזו''א שם סק''ו ד''ה ואם ), e.g., using a crisscross motion or pouring the mixture back and forth between dishes (Issue 349, par. 26).
