In a large Dutch oven or stock pot heat oil at medium or high heat. Season short ribs with salt and pepper.
Sear the short ribs on each side for several minutes, remove from pan, set aside.
Add carrot, celery, garlic and onion to the pot and cook for roughly 10 minutes.
Add the tomato paste and cook for 1 minute. Add the red wine and cook for 1 minute. Add the beef stock and bring mixture to a boil.
Once boiling, reduce to simmer and add back in the short ribs, bay leaf and thyme.
Cover tightly and cook for 3-4 hours, turning and moving the short ribs about halfway through.
Once finished, discard thyme stems and bay leaf. Remove meat from pot and remove from bone if desired and shred lightly. Skim any excess fat from the sauce.