Sear the ribs. Heat a large cast-iron skillet (or other heavy-bottomed pan) over high heat. Once hot, add the oil, and then add the ribs in an even layer. Sear the meat until browned on both sides, about 2 to 3 minutes per side. Transfer the ribs to a slow cooker. (Depending on your pan size, you may need to cook the ribs in 2 batches to avoid over-crowding.)
Cook the aromatics. Turn the heat down to medium-high. To the same skillet, add the onion and garlic and cook for 1 minute, stirring constantly.
Deglaze. Add the wine and cook until it’s reduced to about 1/3 of its volume, about 3 minutes. Use a wooden spoon to scrape up any brown bits that have formed on the bottom of the pan. Stir in the salt, black pepper, beef broth, tomato paste, and Worcestershire sauce. Remove from the heat.
Transfer to the slow cooker. Pour the broth mixture evenly on top of the ribs in the slow cooker. Nestle the thyme, rosemary, and bay leaf into the liquid.
Let it to its thing. Cover and cook on LOW for 10 to 12 hours or on HIGH for 7 to 8 hours.
Serve. Serve the meat along with the sauce to drizzle on top.
Notes
Storage: Store leftovers in an airtight container in the fridge for up to 4 days or freeze for up to 3 months.
Reheating: For best results when reheating, use the oven or stovetop. For the oven method, put the ribs in an oven-safe dish and add a splash of water or broth. Cover the dish and reheat at 300F until warm throughout, about 20 to 30 minutes. Alternatively, you can reheat short ribs (along with the sauce they cooked in) in a saucepan on the stovetop over low heat, stirring occasionally. (Or if you're pressed for time, use the microwave in short bursts, stirring periodically.)