If using a slow cooker, sauté the roast* and add onions, broth, Worcestershire Sauce, and Guinness. Set the slow cooker to Slow Cook and set the timer for 8 hours. Proceed with the rest of the recipe. * If your slow cooker doesn't have a sauté function, sauté the roast in a deep pot on the stove, then transfer to the slow cooker. Try to scrape up any fond that developed in the pot into the slow cooker.