In a small saucepan combine cranberries, orange juice and zest, port, sugar and cinnamon. Bring to a boil, reduce heat to simmering and cook until cranberries are tender, stirring occasionally. In a small cup make a slurry with cornstarch and 1 tablespoon water. Whisk cornstarch mixture into cranberry sauce and cook, whisking, until sauce thickens. Taste and add more sugar, if necessary.
Yield: About 2 cups