In a large pot or Dutch oven, heat the olive oil over medium-high heat. Season the short ribs with salt and pepper, then brown them on all sides, about 5-7 minutes. Remove the ribs and set aside.

In the same pot, add the sliced onions and cook, stirring frequently, until caramelized, about 15-20 minutes. Add the minced garlic and thyme, cooking for an additional 1-2 minutes until fragrant.

Pour in the red wine, scraping the bottom of the pot to deglaze. Allow the wine to simmer for about 5 minutes until slightly reduced.

Return the short ribs to the pot, then add the beef broth, Worcestershire sauce, and bay leaf. Bring to a boil, then reduce the heat to low and cover. Simmer for 2-3 hours, or until the meat is tender and falling off the bone.

Preheat the broiler. Once the short ribs are cooked, remove them from the pot and shred the meat, discarding the bones. Return the shredded meat to the soup.

Toast the French bread slices under the broiler until golden brown, about 1-2 minutes per side.

Ladle the soup into bowls, top each with a slice of toasted bread, and sprinkle generously with Gruyère cheese. Place the bowls under the broiler for 2-3 minutes until the cheese is bubbly and golden.

Garnish with fresh parsley before serving.