Preheat your oven to 325°F (160°C).
Heat the olive oil over medium-high heat in a large Dutch oven. Season the short ribs with salt and pepper and brown them on all sides, about 3-4 minutes per side. Remove and set aside.
In the same Dutch oven, add the onions and carrots. Cook until they are softened, about 5 minutes.
Return the short ribs to the Dutch oven. Add the red wine, beef stock, tomato paste, bay leaf, and thyme. Bring to a simmer.
Cover the Dutch oven and place it in the preheated oven. Cook for 2 to 3 hours until the beef is tender and falls off the bone.
Once cooked, skim off any excess fat and adjust the seasoning as needed.