a paper bag
Put a handful of popcorn in plain white or brown paper bag. Fold the top of the bag over twice. Put it on its side and microwave on high for about a minute at a time, or until you stop hearing popping noises. Season with salt and, if you're feeling wicked, top with melted butter.
That's it. No oil, no butter, and NOT ONE burnt or unpopped kernel.
I bought a stash of white paper packets from the fabulous factory shop Merry Pak & Print when I was last in