Heat the oil in a large skillet. Season the beef all over with salt and pepper. Sear the beef in the pan until you get some good browning all over, about 10 minutes. Transfer the beef to a slow cooker.
To the slow cooker, add the sliced onions, garlic, onion mix, thyme, brown sugar, Worcestershire sauce, and beef stock. Season with a good pinch of salt and pepper, and cook on low for 8 hours.
Bring the milk and water to a light simmer in a small saucepan. Add the polenta and stir on medium, until it begins to slightly thicken and become creamy. This takes about 10 minutes. Off the heat, stir in the butter and parmesan. Season (a bit liberally) with salt and pepper.
Ladle the onions and juices into small bowls, and place a few thick shreds of beef on top of the polenta. Pour the onions and juices over the beef. Garnish with parsley and extra parmesan. Cry for like, ever.
Serves 6. (Or 4, with leftovers. Boom.)
