Contrary to popular belief, new potatoes don't have to be small - they just have to be freshly-harvested potatoes with thin skins and extra sweetness. These don't hold up as well as regular potatoes, so make sure to eat them within a few days and just give them a little brush under running water to take away any dirt and watch the peel come with it. Try and select potatoes of fairly uniform size if you want to cook them all together.