Heat some cooking fat in a large skillet placed over medium-high heat.
Cooking fat
Brown the short ribs on all sides, about 2 to 3 minutes per side. Transfer the short ribs to a slow cooker.
3 to 4 lbs. bone-in short ribs
Add onions, carrots, celery, and garlic to the skillet and cook over medium-high heat, often stirring, until the onions are browned, about 8 minutes.
2 onions, 4 medium carrots, 2 celery stalks, 2 garlic cloves, Sea salt and freshly ground black pepper
Add the tapioca starch and tomato paste to the skillet. Cook, constantly stirring, for 2 to 3 minutes.
2 tbsp. tapioca starch, 1 tbsp. tomato paste
Stir in the wine, and bring to a boil; then lower the heat to medium and let it simmer for 6 to 8 minutes.
1 to 2 cups dry red wine
Add the thyme, rosemary, and bay leaf, stir in the beef stock, and stir until well combined.
3 sprigs thyme, 2 sprigs rosemary, 2 dried bay leaves, 2 cups beef stock
Pour the sauce over the short ribs and cook on low for 6 to 8 hours.