The problem is that all plastics, like the inside of your microwave, are permeable, so the smell is
in the plastic.
Ten minutes in probably too long a time to boil the lemons. Just watch the bowl through the window, when the water is boiling well, shut off the microwave. Leave the door
shut for ten minutes to let the bowl and the lemon steam to cool down.
Wipe out the insides of the oven. Airdry with the door open for a couple of hours.
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If this doesn't work there are other odor removers. OUT is one, it removes all kinds of organic smelly smells (including the always difficult cat pee)
or you can try MEX (a powder non-TSP version of TSP).
http://images.google.com/images?q=tbn:ziHW3wuP1vbGhM:http://www.ugl.com/images/MainMexCln.gif
better still is Oxiclean.
Just mix up a solution of any of these, any swab out the insides of the oven two or three times.
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Butterfly is right about the smoke in the insulation, but the good news is that microwaves are fairly cheap and you can dock the kid's allowance for three years to pay for it.
Joe(burned sock flavor with your popcorn...eeewww)Nation