Prepare glaze in a small sauce pan. Combine cranberries, bar-b-cue sauce, and apple juice. Add the corn starch that has been dissolved in cold water. Cook and stir until thickened. About 5 minutes. Spoon over the pork the last 45 minutes of roasting. Remove roast from oven and skim juices from roast into sauce. Pass with roast to add on sweet potatoes .