Keep your short ribs in the bag they're packaged in. It's designed for your oven.
Thaw in the fridge overnight or until completely thawed.
Place the product in a roasting pan with at least a 2-inch depth. This is to prevent any juices from escaping the bag and making a mess in your oven. This will also make it easier to remove the product from the oven.
Bake for about 4 hours in a 275°F preheated oven. Remove from the oven and let cool for at least 15 minutes before cutting open the bag. Open the bag and serve. Use the juices from the bag for a delicious "au jus."