Add cranberries, orange juice and zest, cranberry juice, sugar and a dash of salt to a medium saucepan. Heat to boiling.
Reduce heat to simmer and cook until the cranberries plump up, about 5 to 10 minutes.
Make a slurry with the cornstarch and water. Slowly drizzle into the sauce mixture while stirring. Stir for at least one minute, until the sauce thickens. Sauce will thicken more as it cools.