Start by browning your beef. Season the flour generously with salt and pepper and then dunk the pieces of beef in the flour. Heat 1 tablespoon of butter in a large pot or dutch oven over medium heat. Once the butter has melted, add the beef and brown all sides of it. I did this in 2 batches, adding more butter with the second batch. Each batch took about 6 minutes to brown.

Once the beef has been quickly browned, place it in a bowl and set it aside. Melt another tablespoon of butter, and add the mushrooms. Season them with salt and pepper. Let cook for 4 minutes, and then add the onions and garlic. After 3 more minutes, add about ½ cup of Guinness - enough to cover the bottom of the pan. Bring to a simmer and add the carrots and potatoes. Let cook for 5 minutes.

Add the remaining Guinness and the beef broth, thyme, and Worcestershire sauce to the pot. Bring to a steady simmer, and return the beef and its juices to the pot. Place a lid on the pot, and let simmer for 90 minutes, stirring occasionally.

If you want to thicken the soup even more, melt a tablespoon of butter and stir in 1 ½ tablespoons of flour, making a paste, and add it to the soup and let simmer for another 10 minutes. Garnish with parsley and serve.