Heat oil in a large skillet or right in your slow cooker if it has a searing option.
Rub some oil over both sides of the meat and sprinkle with the salt and pepper.
Sear the beef on all sides to get a good crust. This takes about 5 minutes per side. Move to a plate and cover with foil.
In the same pan (or your slow cooker), turn down the heat to medium and melt the ghee and add the onions and garlic. Cooking and stirring frequently until the onions are caramelized. This could take about 20 minutes - so worth the wait!
Now add your onions to the slow cooker (if not already in there) and place the seared beef and juices on top of the onions.
Pour in the beef broth, red wine vinegar, thyme and an a extra sprinkle of salt and pepper.
Cover and cook on low for 6 -8 hours. Mine was finished in 6 hours.
Remove from slow cooker and shred the beef and then return to slow cooker and stir with onions and sauce.
Enjoy!