Q: Is it permissible to cook kosher microwave popcorn (sold in a bag) in microwave oven that has not been kashered?

A: Yes, you can use the non-kosher microwave for a bag of kosher popcorn and the only caveats are that (a) the microwave must be relatively clean of all residue and (b) if the bag rips open in the microwave, that whole batch of popcorn will not be kosher.

Open in new window