I cook all my vegetables by placing a steamer basket inside a pot. Using steam to cooking saves a lot of energy because (1) only a small amount of water is heating to boiling, (2) a tight lid allows a higher pressure inside the vessel which, in turn, means a higher cooking temperature and a shorter cooking time, and (3) no steam escapes from the appliance, carrying away all that embodied thermal energy (*). Better yet, your vegetables retain all of their vitamins and minerals (many of which escape when the contents are immersed in water).
Another option is a stand-alone food steamer, which looks like the graphic. It’s an electric appliance (natural gas is a cheaper and more efficient source of heat for cooking) with a thermostat setting for precise temperature control. Most food steamers have several tiers, so you can cook several items simultaneously – vegetables, potatoes, corn on the cob. I’m not big on cluttering up the kitchen with countertop appliances, but if they make it easier to eat at home than dine out (or order in), then by all means – go for it!
* It takes 1 calorie of heat to raise 1 gram of water to 1 C. Once the water reaches boiling point, 100 C, it takes 540 calories per gram of water to create steam. When you boil anything in an open pot, all that thermal energy escapes! And so, even if you don’t have a steamer basket – keep a lid on all your pots!