If bicarbonate of soda works for fridges and keeps them odour-free perhaps it will work for microwaves too?

Also, I know that a little instant coffee mixed with water and rubbed over your hands removes onion smells so perhaps a little rubbed around the microwave might neutralise the smell?

Only other thing I know that removes smells is crushed parsley.

There you go, I'm all out of odour removal ideas now - hope one of them helps.

Snork Maiden