Well, despair no more! While the title of the article sounds a wee bit unfortunate - Grow Food Scraps Indoors - the article does offer some good ideas for growing food in pots, including green onions. A good list of vegetables and some nice details about how to manage the indoor container garden can also be found here.
And just as a little extra, this blog post focuses mostly on growing in containers outdoors, but it offers sound advice on selecting containers and the unique needs of such plants. Enjoy!