Toss the beef chunks with the flour until lightly coated.
Heat the olive oil in a skillet over medium-high heat. Add the beef and brown on all sides for about 5 minutes. Transfer the beef to the slow cooker.
Add the diced onion and minced garlic to the same skillet. Cook for 2 minutes, stirring often, then scrape everything into the slow cooker.
Place the sliced carrots and cubed potatoes into the slow cooker. Pour in the brown ale and beef broth. Add the thyme, salt, and black pepper.
Stir gently to combine all ingredients. Cover and cook on low for 7 to 8 hours.
Stir the stew once more before serving to check the gravy thickness.