I'm confused by some of the rabbinical advisory websites regarding what dishware can be kashered. Evidently glass and ceramic, the most convenient microwave safe materials, according to Askkenasi cannot be kashered and therefore can't be used for kosher service. Are there ANY microwave-safe materials for dishes which CAN be kashered?
For plates and soup bowls, the most convenient articles would be those of plain (without ornamentation) steel or aluminum.
It is a commonly believed myth that no metal items can be safely used in a microwave oven. A clear indication of this assumption's falsity is the fact that the insides of the appliance are metal, and some ovens even have metal turntables or racks:
The truth is that smooth metal objects are perfectly safe in microwave ovens, however the food to heat slower if extensively covered. Therefore, smooth plates and open bowls are kasherable microwavable dishware.
Do not attempt to use any non-smooth metal object in a microwave, such as torn or crumbled aluminum foil, aluminum trays, ornamented plates, forks, serrated knives, etc. Doing so may cause arcing, property damage, and injury!