4. For the potatoes: About 30 minutes before serving stew, put potatoes in a medium pot with cold water to cover. Add salt and bring to a boil over medium heat. Simmer until potatoes are soft, about 20 minutes. Meanwhile, bring milk and butter to a simmer in a small saucepan over low heat. Drain potatoes and return to pot over medium heat, shaking until potatoes become dry and mealy. Mash potatoes with a masher; gradually whisk in milk mixture and season to taste with salt and pepper. Serve stew over potatoes. Garnish with parsley, if you like.