Set the slow cooker to low.
Combine all ingredients except cornflour, and add to the slow cooker bowl.
Cook on low for 8 hours.
For a thicker sauce, 30 minutes before serving ladle ¼ cup of the sauce into a small bowl and whisk the cornflour or arrowroot into it with a fork. Return mixture to the slow cooker bowl, stir through and leave for a further 30 minutes.
Serve with mash and vegetables of your choice.