A food that become ossur "c'dei klipah" (a "peels worth") from some sort of issur (prohibited food) is one allowed to remove the "klipah" on Shabbos? Is this an issue of borer (separating?) Are there any poskim that speak about this particular case (beside from any answer where one may draw a similarity from this case to another.)
Note: One could ask if there perhaps is a problem of "fixing" the food. There is already much discussion about makeh b'patish b'ochel. However I'm more asking about the problem of borer in this case.