Reduce the quart of beef stock to one cup in a deep sauté pan and set aside. Season the short ribs with salt and pepper, and then dredge in flour until well coated. Heat the olive oil in a large frying pan over medium-high heat. Cook the dredged ribs until browned on each side, about 5 minutes per side. When browned on both sides, remove the ribs from the skillet and set aside. Reserve pan drippings for later.
To a slow cooker, add the onion as a bed, then add seared short ribs. Add any juice or drippings reserved from the pan. Cover the ribs with smashed garlic cloves, fresh herbs, butter, salt and fresh cracked pepper. Add the stout beer and reduced beef stock. Place the lid on the slow cooker and set to high.
Cook for approximately 6 hours or until tender. Top short ribs with sauce made from cooking them. Serve with rice.