With the rack in the middle position, preheat the oven to 165 °C (325 °F).
In a large saucepan or Dutch oven, brown the meat in the butter and oil. Season with salt and pepper. Keep the meat aside on a plate.
In the same pan, brown the onion. Add oil, if needed. Sprinkle with the flour and stir to combine. Deglaze with the beer and bring to a boil, stirring constantly.
Return the meat to the pan. Add the broth, turnips, and carrots and bring to boil. Season with salt and pepper. Cover and bake for 2 hours. Add the potatoes and prunes and stir to combine.
Cover and cook for about 1 hour or until the potatoes are cooked and the meat is fork-tender. Add the parsley and adjust the seasoning. If desired, serve with sour cream. ??.
Tips: The classic "Irish Stew" was originally prepared with mutton, root vegetables, and water. After the great famine of 1845 and the emigration of a portion of the population, the dish evolved and includes ingredients easier to find in their new land, such as beef. Finally, we replaced the water with Guinness, the flagship beer of the Irish culture. For this recipe, you can substitute it with the beer of your choice.