In a small bowl mix the red wine, mustard, salt, and pepper and place in the insert of the slow cooker. Layer the shanks in the insert so they fit. Scatter the remaining ingredients around and on the shanks. Cover and cook on HIGH for 6 hours. Use tongs to reverse the position of the shanks, top to bottom. Reduce the setting to LOW and cook for an additional 6 hours.
Use a slotted spoon to transfer the shanks to a serving platter. Skim the fat from the cooking juices, taste, and add salt and pepper, if needed. Pour the juices over the shanks, and serve.
For a less assertive garlic taste, use elephant garlic.