Grind strawberries and cranberries in a food processor or grinder; place in a Dutch oven. Add sugar. Bring to a full rolling boil; boil for 1 minute. Remove from the heat; stir in pectin and return to a full rolling boil. Boil for 1 minute, stirring constantly. Remove from the heat.
Cool for 5 minutes; skim off foam. Carefully ladle hot mixture into hot half-pint jars, leaving 1/4-in. headspace. Remove air bubbles; wipe rims and adjust lids. Process for 10 minutes in a boiling-water canner.Yield: about 14 half-pints.