Is it allowed to sell “challah” (trumah) to a goy? i.e. someone that was unable to get rid of their challah before Pesach (yes, I realize it sounds funny since there is a fire to burn it in on every corner!) may they sell it to goy before the zman issur?
This is certainly an unusual question.
There is no prohibition of selling terumah or challah to a non-Jew; although the Mishnah indicates (Terumos 8:11) that one can’t give terumah to a non-Jew for him to make it tamei, this doesn’t apply to a regular sale (see Niddah 6b and Tosafos Berachos 47a and Eiruvin 17b), and in any case today’s terumah might be different because we dispose of it and don’t eat it.
The problem of causing a takalah doesn’t apply either, because the non-Jew is certainly not going to give the chametz to another Jew.
Therefore, there is no problem.