Whats the best way to prepare mashed avocado on shabbos? Can it be smeared on bread with a knife or spoon?
Answer:
For avocado, some authorities are lenient to mash it with the teeth of a fork (provided it is done for immediate consumption), whereas others are stringent, and require a shinui–for instance, mashing with the back of a spoon.
According to Rav Moshe Feinstein, it is permitted to mash an avocado or a banana (Iggros Moshe, Orach Chaim 4:74, Tochen 2), if this is done right before the meal.
The reason for this is that no pieces are ground, and because the Rashba rules it is permitted to grind for the purpose of immediate consumption. Also, many maintain that when a food is already fit for consumption, the prohibition of grinding does not apply.
However, the Chazon Ish is stringent in this matter, as is Shemiras Shabbos Kehilchasa (6:1). Yet, all agree that it is permitted to mash the avocado by using the back of a spoon, which is not the regular way of mashing it.
If the avocado is already soft, it is permitted to spread it gently on bread.
