Heat olive oil in heavy large pot over medium-high heat. Add diced beef and sauté until brown on all sides, about 5 minutes. Add garlic and sauté 1 minute. Add beef stock, Guinness, red wine, tomato paste, sugar, 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 is 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 stew in step one has simmered for one hour.
Add vegetables to beef stew. Simmer uncovered until vegetables and beef are very tender, about 40 minutes. Discard bay leaves. Tilt pan and spoon off fat. Transfer stew to serving bowl.
(Can be prepared up to 2 days ahead. Salt and pepper to taste. Cool slightly. Refrigerate uncovered until cold, then cover and refrigerate. Bring to simmer before serving.).