People are sometimes unaware of the requirement of M’yad (Immediate Use) when peeling fruits, vegetables or eggs for a salad. For example, when preparing eggs for an egg salad, one must remember to peel the eggs just before the meal, and not earlier. When making a fruit or vegetable salad one should also prepare the salad immediately prior to use. Also, if one cuts very small pieces, this would involve a question of Tochain (Grinding). Thus, one should cut the pieces slightly larger than usual.
Shulchan Aruch w/Mishnah Berurah 321:19, Igros Moshe OC:4:74:8, SA 321:12,45, Sefer 39 Melochos
Review: How Long Is Considered M’Yad
There is in fact no precise unit of time by which to measure and determine Miyad – Immediate Use. Rather, the criteria for Miyad are relative to the circumstances. As a rule, whatever time is needed by a particular individual to prepare a particular food or meal (or objects for use) is considered Miyad, and one may begin sorting or selecting within that period. Examples:
Preparation for a meal is underway and a variety of chores, some of which involve Borer, are necessary (e.g. sorting mixed silverware, peeling eggs, peeling vegetables). It is permitted to do the Borer activities (so long as all 3 conditions prevail) anytime during the entire course of preparation of the meal even though the selected items will not be used until much later in the meal, (even if the course of preparation includes non-Borer activities). So that even if the entire preparation will take an hour or more it is considered Miyad. However, one would not be permitted to complete the preparations and then take a two minute walk, and then sit down for the meal, because the extra two minutes are not part of the preparation and even a very brief unrelated delay is no longer considered Miyad.
Shulchan Aruch w/Mishnah Berurah 319:1, see Biur Halacha there, SA 321:MB45, Igros Moshe OC:4:74:13, Shemiras Shabbos Kehilchasa 3:20, Sefer 39 Melochos