Skillet-Roasted Rosemary Potatoes

"The best kind of pan for roasting these potatoes is an old-fashioned cast-iron skillet. I use a 10-inch skillet for about 8 potatoes (16 halves), but if your skillet is 12 inches, you can fit 10 potatoes (20 halves). I prefer smallish potatoesâ??2 or 3 inches in diameterâ??cut just in half, which keeps the interiors moist and creamy. I like to use coarse sea salt, as the large crystals give a nice crunch without oversalting the potatoes, but kosher salt works nicely, too...."