Steaming and boiling both use moist heat, so it's logical to assume you would get the same result by cooking potatoes with either method -- but not so. During boiling, potatoes jostle in the water and bump against each other, which releases their starch; the more starch they release, the gummier they become. Potatoes steam undisturbed, so the starch remains in their cells; the more starch that remains in the cells, the less gummy they become, yielding a lighter, fluffier potato dish.
Scrub the potatoes under cool water. Peel the skins, if desired. Cut the potatoes into 1- to 1 1/2-inch cubes to use them in a salad or mash them; leave the potatoes whole or quarter them for other uses. Place the potatoes in a bowl of cold water right after you cut them to prevent them from turning brown.
Fill a pot with 3 to 4 inches of water. Keep the water level at least 1/2 inch below the bottom of the steamer insert.
Bring the water to a boil. Place the cubed potatoes in an even layer in the steamer insert and cover the pot.
Steam the potatoes until they pierce easily with a fork, about 15 to 20 minutes for cubes and 20 to 25 minutes for halves or quarters. Let the potatoes cool to room temperature before placing them in the refrigerator for use in a salad or other cold dish.