01 -
Pat the beef short ribs dry with paper towels. Season generously on all sides with salt and freshly ground black pepper.
02 -
Heat olive oil in a large heavy-bottomed pot over medium-high heat. When shimmering, add the short ribs and sear on all sides until deeply browned, about 2-3 minutes per side. Remove ribs and set aside.
03 -
Add thinly sliced onions to the same pot using the rendered fat. Reduce heat to medium-low and cook, stirring occasionally, for 30-40 minutes until onions are deeply golden and reduced. Add minced garlic in final minute and cook until fragrant.
04 -
Pour in beef broth, scraping the pot bottom to lift browned bits. Stir in balsamic vinegar, thyme leaves, and bay leaf. Return short ribs to the pot and bring to a gentle simmer over medium heat.
05 -
Reduce heat to low, cover tightly, and simmer for 2 to 3 hours until ribs are fork-tender. Stir occasionally and add broth or water if liquid reduces too much. Adjust seasoning with salt and pepper.
06 -
Preheat broiler to high. Remove ribs from soup; shred meat if desired and discard bay leaf. Ladle soup into oven-safe bowls, top with sliced bread, and generously cover with shredded cheese. Place bowls on baking sheet and broil for 2-4 minutes until cheese is melted and golden. Serve immediately.