I left out the margarine (got my onions softer in the microwave), flour, and most of the soymilk; I used frozen green beans instead of canned; I added a diced red bell pepper to the green beans for visual interest, and I added dressing mix to the mushroom mixture for an extra kick of flavor.
Yum, yum, yum!
The mushroom mixture didn't resemble cream of mushroom soup since I left out the soymilk, but that was to our advantage so that the fussy children could easily pick out just the green beans to eat while the rest of us mixed everything together. This was sooo tasty! Not as traditional as the soupy kind, but the same flavors only better!