i've been cooking my vege's using the bag methd for awhile , quite a good idea
here is my method for steamed vege's
Put vegetables of choice in a freezer bag or the platic bag you get from the vege department, add a little bit of water, put them in the microwave with the top of the bag tucked under so that steam can't escape. microwave for for 2-4 minutes, depending on how much you've got. The bag will be hot when you take it out though, so watch out for the steam.
Works a treat for green beans, carrots and broccoli, not so well for cauli though.