Hacham Ovadia Yosef, in his Yehaveh Da’at (1:11), addresses the case of jelly that was prepared before Pesah with only kosher-for-Pesah ingredients, but in pots that had been used with Hametz and were not koshered for Pesah. Assuming the pot was perfectly clean when it was used for preparing the jelly, may the jelly be eaten on Pesah, as it does not contain any Hametz, or is it forbidden on Pesah because it absorbed the taste of Hametz from the walls of the utensils in which it had been cooked?
Hacham Ovadia permits eating the jelly in such a case, noting two reasons why it should not be considered Hametz. First, we generally assume that most pots are not "Beneh Yoman," meaning, they had not been used within the previous twenty-four hours. In light of this assumption, any Hametz flavor in the walls of the pot used for the jelly had been absorbed in the walls for at least twenty-four hours, and thus the flavor is considered "Noten Ta’am Li’fgam" – that is, it imparts a foul taste in the food. A negative taste of Hametz does not render food forbidden on Pesah, and thus the jelly is permissible. Additionally, the Hametz taste absorbed by the jelly is "Noten Ta’am Bar Noten Ta’am," or a "second degree" taste. The jelly does not directly absorb a taste of Hametz, but rather absorbs a taste of Hametz which had been absorbed by the walls from the Hametz that had been cooked in the pot. Halacha permits a "Noten Ta’am Bar Noten Ta’am" if the taste in question was not forbidden for consumption at the time it is absorbed. In this case, the jelly was prepared before Pesah, when Hametz was not yet forbidden. As such, this taste is permissible, even once Pesah begins.
A similar case is where one mistakenly used an ordinary, Hametz pot on Pesah to prepare rice. Sepharadim allow eating rice on Pesah (as long as it had been checked three times for Hametz), but of course the rice should be prepared in a special Pesah pot, or in a pot that was koshered for Pesah use. Nevertheless, if one mistakenly used a regular, Hametz pot (which had been cleaned but not koshered), the rice may be eaten on Pesah. As in the case of the jelly, the taste of Hametz in the walls of the pot is more than twenty-four hours old, and therefore the rice is permissible for eating on Pesah. It goes without saying that this applies only "Be’di’abad," after the fact, and optimally, as mentioned, one should use specially-designated Pesah pots, or koshered pots, for preparing food for Pesah. But if such a mistake happened, the rice is permissible.
Summary: If jelly was prepared before Pesah in a pot which was not koshered for Pesah, the jelly may nevertheless be eaten on Pesah, assuming the ingredients are all kosher for Pesah and the pot was clean. If one mistakenly prepared rice on Pesah in a Hametz pot, the rice is nevertheless permissible on Pesah.
