Heat a large skillet over medium-high heat and brown the beef stew meat in batches until all sides are seared. Transfer the meat to the slow cooker.
Add the potatoes, cabbage, carrots, onion, and garlic to the slow cooker with the beef.
In a bowl, whisk together the Irish stout, beef broth, tomato paste, thyme, salt, and black pepper. Pour the mixture over the ingredients in the slow cooker.
Add the bay leaves on top. Cover and cook on low for 8 hours.
Remove the bay leaves before serving.