Preheat your oven to 300°F (150°C).
Season the beef short ribs with salt and pepper.
Heat olive oil in a large oven-safe pot over medium-high heat.
Sear the short ribs on all sides until browned, about 5-7 minutes.
Remove the ribs and set aside.
In the same pot, add diced onion and sauté until translucent.
Stir in minced garlic and cook for 1 minute.
Add beef broth, red wine, tomato paste, brown sugar, and thyme to the pot.
Return the short ribs to the pot, ensuring they are submerged in the liquid.
Cover and transfer to the oven; cook for 3 hours until tender.