Season the beef with 2 teaspoons of the salt. Heat the oil in a large stockpot or Dutch oven over medium-high heat. Brown the beef on all sides in batches, being careful not to crowd the pot. Remove to a plate.
Add the potatoes, carrots, and onion to the pot. Cook, stirring frequently, for 10 minutes. Remove and set aside.
Add the garlic to the pot and cook 1 minute or until fragrant. Stir in the tomato paste, beef stock, red wine, Guinness, and thyme, scraping up any browned bits from the bottom of the pot.
Return the beef and any juices to the pot. Bring to a boil, then reduce to a simmer and cover. Cook 1 hour or until the meat begins to get tender.
Add the vegetables back to the pot and cook 20 to 30 minutes, until the potatoes, carrots, and beef are tender. Season with the remaining salt and black pepper to taste.
Notes
Depending on the saltiness of your beef stock, you may want to adjust the salt added to the beef at the beginning and at the end of cooking.For a thicker broth, mash a few potatoes against the side of the pot and stir them in.