Begin by heating the olive oil in a large pot over medium-high heat. Season the short ribs with salt and pepper, and sear them for about 3-4 minutes on each side until golden brown. Remove the ribs and set them aside.

In the same pot, add the sliced onions and reduce the heat to medium-low. Cook them for approximately 20-30 minutes, stirring occasionally, until they turn deeply caramelized and sweet.

Stir in the minced garlic and cook for another minute until fragrant.

Pour in the balsamic vinegar to deglaze the pot, scraping any brown bits from the bottom.

Return the short ribs to the pot and add in the beef broth, thyme, bay leaf, salt, and pepper. Bring it to a simmer.

Cover the pot and let the soup simmer on low heat for about 2-3 hours, or until the meat is tender and easily shredded.

Once cooked, remove the short ribs, shred the meat, and discard any bones. Return the meat to the soup.

Ladle the soup into bowls, top with toasted baguette slices, and generously sprinkle with Gruyère cheese.

Optional: Pop it under the broiler for a minute if you want the cheese extra melty!