Is the preparing of a potato salad a problem of 'lisha'?

An important factor constituting ???? is the binding of solids. In order to determine whether ???? is taking place one must find out whether the solids our being bound together or are merely being covered in liquid.

The Mishna Berura [1] tells us that there is no problem mixing lettuce salad (with a liquid) because the lettuce is not cut up finely enough to cause a problem. On the other hand he says, people who usually cut radish and cucumbers finely and pour vinegar or other liquids over them and mix them are violating the prohibition of 'lisha'.

In this latter case he says the solution is to mix the ingredients slowly and l’chatchila first pour the vinegar and only then add the solids to the liquid. [2]

In the last shiur we preferred mixing the ingredients in such a case in a crisscross fashion or with one’s finger.

Reverting to our question we see that large pieces are not subject to the constraints of 'lisha' and therefore mixing mayonnaise and potato salad is permitted as it is not called 'lisha'. [3]

One may mix carrots and orange juice on Shabbos because the resulting mixture does not resemble 'lisha' at all.

What about mixing orange or lemon juice and cream cheese or sour cream?

In this case the fruit juice does not bind solids, on the contrary, it dilutes the solids, which is contrary to the definition of ????, and therefore it is permitted. For this reason Rav Shlomo Zalman Auerbach ztz”l [4] permits adding sugar to sour cream because the sugar becomes liquid and dilutes the sour cream.

Is there a problem preparing instant mash on Shabbos?

The answer depends on the method of preparation of that particular instant mash.

If the mash binds upon the pouring of the water and needs hardly any mixing then one may not prepare such a mash on Shabbos. This is because the Shulchan Aruch says [5] that one may not throw flax seeds into water on Shabbos because they bind without further human intervention.

If one is required to stir the mash in order to prepare it, since it is a ????? ??? – a thick consistency, and only if it would spoil if prepared before Shabbos, one may then prepare it on Shabbos by stirring it in a crisscross fashion. It is correct to modify the pouring order as well. [6]

Many people make their own tehina solution. Is it permitted on Shabbos as well?

Preparing a tehina mixture (ground sesame seeds) on Shabbos is a classical case of a ????? ??? and preparation is prohibited on Shabbos. If one would make it into a liquid solution, one would then modify the pouring order and mix it by either shaking the bowl or in a crisscross manner.

However, one may prepare a thick consistency before Shabbos and dilute it with water and other liquids on Shabbos, provided that it was well mixed before Shabbos. [7]

May one add mayonnaise to tuna fish on Shabbos?

Preparing a tuna fish salad shares the same halacha as preparing egg salad on Shabbos. We saw in the previous shiur that many are accustomed to preparing the egg salad on Shabbos. There definitely is preference for preparing it before Shabbos but if this is not done,[8] there is what to rely on for preparation on Shabbos. It is desirable, according to some opinions, to modify the pouring order and mix it in a crisscross motion.

What if someone prepared a mixture contrary to the halacha b’shogaig (unwittingly). May it be eaten on Shabbos?

As with all such cases, when it is strictly forbidden and not merely stringency, the person that prepared it and the persons whom it was intended for may not eat it until after Shabbos. The Vilna Ga’on holds that they may it eat it on Shabbos and the M”B [9] writes that when necessary one may rely on the Vilna Ga’on. [10]