Microwave oven (Kashering) Status: May be kashered for Passover or year-round, except the glass plate To kasher, clean microwave thoroughly and do not use for 24 hours. Boil a cup of water in the chamber for an extended amount of time, until the chamber fills with steam. The glass plate cannot be kashered (or used) and should be removed before kashering begins. For convection microwave ovens, the same kashering process as a conventional oven should be followed, paying particular attention to cleaning out the chamber and fan assembly. For Pesach, it is a commendable extra precaution to cover all foods in the microwave, even after performing the above kashering. [Microwaves with a porcelain enamel interior cannot be kashered.]