New potatoes are freshly harvested young, or small, potatoes. They have paper-thin skins and lots of moisture inside, and they tend to be sweeter than older potatoes (in much the same way that freshly picked corn is so much sweeter than cobs that have been sitting around for a few days). New potatoes are pure perfection in potato salads or simply boiled with a bit of butter and a few chopped herbs.
How to Choose New Potatoes
Look for new potatoes that have smooth, undamaged, and unblemished skins. The potatoes should be dry and fell firm. Avoid potatoes that have soft spots, bruising, or seem damp or wet. Skins that are starting to flake away from the potato are fine - that's the price of such youth and delicacy! Ditto re: dirt. New potatoes are freshly harvested and a bit of dirt just shows that they really are new potatoes and not just small potatoes.
Look for new potatoes in the spring and early summer.
How to Store New Potatoes
Because they have such thin skins and high moisture levels, new potatoes don't keep as well as more mature potatoes. Keep them in a paper bag or loosely wrapped plastic in the fridge and use new potatoes within a few days of buying.
Don't fall prey to the temptation to wash new potatoes before storing them. That bit of dirt clinging to their skins will actually help keep them fresh and any water on the outside will hasten bruising and softening.
How to Cook New Potatoes
New potatoes are classically served simply boiled and buttered. Rinse any dirt off the new potatoes' skins and put them in a large pot. Cover new potatoes with cool water and bring everything to a boil. Add enough salt to make the water taste a bit salty (this is how the potatoes get seasoned, so don't be stingy!) and cook, gently boiling, until the potatoes are fully tender, 10 to 15 minutes. Drain the potatoes, shaking off as much water as possible. Transfer the potatoes to a serving dish and top with pats of butter. Gently toss to melt the butter and coat the new potatoes simultaneously. Sprinkle with chopped parsley or other green herbs, if you like.
While not a traditional preparation, new potatoes can also be roasted. Because of their slightly waxy texture and tendency to keep their shape, new potatoes don't make great mashed potatoes, but you can use them to make Smashed Potatoes.