Cleaning a microwave oven

The levels of dried-out burnt-on food on the roof of our microwave oven were well below bachelor-tolerance levels, and, considering the dose of radiation they had received, either totally sterile or already in possession of super powers. However, with my wife due back the next day, a fab-like level of cleanliness was highly desirable...

The first attack (dish-scrubber) was easily repulsed; the fossilized remnants of dinners past appeared to have attained an inter-molecular level of integration with the substrate. Doubled the elbow-grease factor, tried again, same result. Next, considered the array of chisels, lump-hammers, power saws, angle-grinders available to me, but rejected them on grounds of safety (mine, on the return of She Who Must be Obeyed). What to do?

Then, the light bulb moment. I got a bowl full of water (just water), deployed it to the centre of the oven, and gave it 8 minutes at 800 watts. Opened the door again to a steam-blasted oven that came clean on the first wipe. Result!.