Step 1

Brown the beef, transfer to slow cooker: Heat the butter in a large sauté pan over medium-high heat. Brown the beef in the butter, starting with the fattiest pieces of meat, fat side down in the pan. This will allow some beef fat to render out. Work in batches as to not crowd the pan.Sprinkle salt over the beef as it browns. Once browned on all sides, transfer the beef pieces into a 6-quart or larger slow cooker.

Step 2

Sauté onions and celery, transfer to slow cooker: Add the onions and celery to the pan in which you just browned the beef. Sauté the onions and celery until they begin to brown at the edges, about 5 minutes.Add the tomato paste and mix well. Cook for a minute or two, then add a little of the Guinness, enough to make it easier for you to scrape up any browned bits at the bottom of the pan.Transfer the celery and onions into the slow cooker.

Step 3

Add Guinness, broth, root vegetables, thyme, salt: Add the rest of the Guinness, the beef broth, carrots, parsnips, celery root, and thyme to the slow cooker. Add two teaspoons of salt.

Step 4

Cook in slow cooker: Cover and cook on "high" for 4 hours, or "low" for 8 hours. When done, add more salt to taste. If you want, sprinkle with fresh parsley to serve.