6.a. It is in general forbidden to grate, chop or shred raw food of a kind which grows in the ground, such as uncooked fruits or vegetables.
6.b. It is permissible to cut up such food with a knife, provided that
1) the resulting pieces are not too small and
2) the meal at which the food is to be eaten follows immediately.
6.c. There is good authority for allowing a person who is preparing food for a small child, or for someone who would otherwise find the food difficult to eat, to cut it even into very small pieces, so long as he does so immediately prior to the meal.