Before Pesach, may one prepare kitniyos on a kosher lpesach stove top – as well as cleaning those pots in hot water in the sink. What are the status of the pots where kitniyos was used before pesach if they are ben yomo or eino ben yomo?
It is permitted to prepare it on a kosher for Pesach stovetop, however you should be careful that it shouldn’t spill over etc. Regarding washing them in the sink, although it is better to do it in a different sink so that the leftover kitniot does not mix with the pesach food, technically it is permitted, but it shouldn’t be done in hot water as the taste will go to the other pots. If the pots that were used to cook kitniot are not ben yomo they are alright and may be used, however if the are still ben yomo they should not be used for regular pesach food according to many poskim, since they will give the pesach food the taam of the kitnios. Nevertheless there are people that have separate pots for kitniot that has to be cooked.
Have a chag kasher v’sameach
Pri Chadash O:CH 496, Kaf Hachayim 453- 27, Graz 464-2, Although kitnios that that fell into the pesach food and got mixed in is permitted to eat, that is only if it got mixed in accidentally, but not if it was mixed in intentionally. Cooking with a ben yomo pot is like mixing the kitniot in purposefully. Shut Maharam Shick O:CH 241