Heat olive oil in heavy large pot over medium-high heat. Lightly salt the beef pieces. Add the beef and cook, without stirring, until nicely browned on one side, then use tongs to turn the pieces over. Continue to cook in this manner until all sides are browned, about 5 minutes. Add garlic and sauté 1 minute. Add beef stock, Guinness, red wine, tomato paste, sugar, thyme, Worcestershire sauce, and bay leaves. Stir to combine. Bring mixture to boil. Reduce heat to medium-low, then cover and simmer 1 hour, stirring occasionally. While the meat and stock are simmering, melt butter in another large pot over medium heat. Add potatoes, onion, and carrots. Sauté vegetables until golden, about 20 minutes. Set aside until the beef mixture has simmered for one hour. Add vegetables to beef mixture. Simmer uncovered until vegetables and beef are very tender, about 40 minutes. Discard bay leaves. Tilt pan and spoon off fat. (If you like a thick stew, take a tablespoon or two of flour, mix with 1/4 cup water, and stir into to the stew to thicken.) Transfer stew to serving bowl. Add salt and pepper to taste. Sprinkle with parsley and serve. Serves 4 to 6.