Trim off the ends and any rough spots from the zucchini, but do not peel it.
Slice the squash and scallions very thin.
Place half the sliced squash in a saucepan.
Add the scallions and then the remaining squash.
Cover tightly and place over moderate heat, shaking the pan frequently the first five minutes of cooking to prevent sticking.
If necessary, add the water.
After it has started to cook well, reduce the heat to low and let steam until done, fifteen to eighteen minutes.