I’ve got really into this idea recently. Basically, you just wrap some vegetables in an aluminum foil parcel and throw them in the oven with whatever else you are cooking. I’d seen this done a lot with fish and figured it would work well with vegetables — it does.
The difference from other methods of steaming is that it keeps all the flavor of the veggies sealed in. It also means you don’t need a pan (or pans) to cook your side, you just prepare your parcel (or parcels) earlier and put them in when your roast or whatever is almost done.
So far I’ve only tried the string beans and the zucchini described here, but I guess it would work with anything: carrots, broccoli, even spinach.
String beans
Zucchini