Can tehini be mixed on Shabos as a cold salad? The sesame seed paste is ready bought and needs water, salt, chopped garlic, lemon juice and some milled pepper.
Tehina should be prepared before Shabbos. The preperation of tehina may involve the prohibition of Losh, kneading a substance on Shabbos. This may be applicable when adding water to the tehina which initially creates a hard non pourable substance, before becoming a loose substance. There is also this problem when mixing the crushed garlic pieces in with the tehina.
Shemiras Shabbos Kehilchasah (8:26) prohibits preparing tehina, because of an interim stage when the mixture becomes harder, which is considered kneading.
Yet, some rule leniently concerning preparing tehina, for a number of reasons:
1. We do not look at the interim stage, but only at the final product, whereby a thick mixture is made thinner.
2. According to some Rishonim (Rashba), the prohibition does not apply right before the meal.
3. According to some authorities, there is no prohibition of kneading after a dough has already been kneaded (Shulchan Aruch 321:15; see Chazon Ish).
Therefore, some permit preparing tehina on Shabbos, if a shinui is made in mixing it (for instance, mixing in criss-cross action rather than bringing the spoon round), and if it is prepared right before the meal.
Although one should prepare the tehina before Shabbos, there is therefore room to rely on the lenient opinion where there is a need.
See also Menushas Ahava Vol. 2, 9:17.