Heat cooking oil in a large pot
Add cubed beef, season with salt and pepper, and dredge with flour
Sear the beef until browned on the outside
Remove the beef and set aside
Deglaze the pot with Guinness, scraping up the browned bits
Add the chopped onion, carrot, and celery, and cook for 4-5 minutes
Stir in the tomato puree and crushed garlic
Add the beef stock, bay leaf, and thyme
Return the seared beef and its juices to the pot
Cover and simmer for 2 hours
Add the chopped potatoes and cook for an additional 45 minutes
