In a large stockpot, add oil; bring to medium heat and add bacon; cook bacon until it is somewhat crisp; use a slotted spoon, remove bacon bits and place on paper towel
Working in batches, add cubed beef to the stockpot; brown meat on all sides; remove beef from stockpot and set aside
Deglaze the stockpot: Pour Guinness Stout beef into the stockpot; bring heat to high and use a wooden spoon to scrape any remnants from the bottom of the pan
Add onions, carrots and celery to stockpot; allow to cook for 3 minutes
Add seared beef, cooked bacon, beef broth, tomato paste, potatoes, thyme, Worcestershire sauce and bay leaves to the stockpot; cover and allow to simmer for 50 minutes; check the liquid level frequently; if the liquid begins to absorb, add more beef stock or water
If you want to make this delicious Irish-American stew in a crockpot, just brown the beef on the stove top first, then add all the ingredients to the slow cooker. Make sure the liquid covers the meat and vegetables, and cook on low 5-7 hours.
If you want a thicker stew, make a slurry of 2 tablespoons flour in one cup of warm water; mix together and add to stew