In a small saucepan, combine one bag of cranberries, orange zest. orange juice, and sugar. Bring to boiling, then reduce heat to low. Simmer, about 3 minutes, stirring occasionally, just until some of the cranberries pop and all of the sugar is dissolved. Remove from heat; cool.
In a food processor, combine the remaining bag of cranberries, quartered orange, and salt; pulse 6 or 7 times until coarsely chopped. Stir chopped cranberry mixture into cooked cranberries. Cover and refrigerate relish up to 3 days.