In a large saucepan, combine potatoes and water to cover. Bring to a boil over medium-high heat; reduce heat, and simmer until potatoes are very tender, about 15 minutes. Drain well, and return potatoes to pan. Add butter, buttermilk, sour cream, salt, and pepper. Mash with a potato masher until desired consistency is reached.
Recipe by Victoria at https://victoriamag.com/ale-braised-short-ribs-mashed-potatoes-kale-recipe/