Can one rely upon a non-Jew to determine if a non-Kosher food product is charif (sharp)?
One can rely on te’emas k’failah to determine if non-kosher food is charif. Although Rema Y.D. 98:1 rules that we generally do not rely on te’emas k’failah, in this case we would agree with the Shulchan Aruch who would permit it.
