In a large pot or Dutch oven, heat olive oil over medium-high heat. Season the beef cubes with salt and pepper, then add them to the pot in batches. Brown the beef on all sides, then remove from the pot and set aside.
Stir in the tomato paste and cook for a couple of minutes until it caramelizes slightly.
Pour in the Guinness beer and beef broth, scraping up browned bits from the bottom of the pot with a wooden spoon.
Return the beef to the pot along with the carrots, potatoes, bay leaves, and thyme. Stir to combine.
Cover and reduce heat to low, simmer for about 2 hours until beef is tender and flavors meld.
If a thicker stew is desired, mix flour with water to make a slurry, stir into the stew, and simmer for an additional 10 minutes.
Notes
For best results, allow the stew to sit overnight for the flavors to meld before refrigerating. When ready to eat, simply reheat and enjoy your flavorful stew.