Cook the potatoes in whatever way you usually do, until tender, and mash until smooth. I like to use a potato ricer (sort of a large garlic-press type device); it’s fast and eliminates all the lumps. Add the sour cream and salt, and beat until thoroughly combined. Don’t overbeat or the potatoes will get gummy. Scoop your mashed potatoes into ice cream cones, pushing the filling right to the bottom so they don’t topple over. Stand them up on a cookie sheet or muffin pan and heat in a 350°F (180°C) over for about 10 minutes.