In a medium saucepan, bring sugar, water, cinnamon, and salt. to boil. Stir occasionally to dissolve the sugar.
Stir in cranberries and apples. Simmer until slightly thickened and the berries begin to pop, about 10 minutes. Remove from heat and cool to room temperature or chill.
Cranberries: Fresh cranberries freeze really well, so stock up when you see them. If your cranberries are already frozen, no need to thaw. Just cook them straight from the freezer and add 2 minutes to the simmering time.
Apples: I like tart Granny Smith apples because they hold their shape in the sauce.
Yield: This recipe makes 3 cups of sauce, enough for 12 (1/4 cup) servings.
Make ahead: Cool the cranberry sauce completely, then keep refrigerated for up to 3 days. Or, freeze it up to one month in advance. Thaw in the refrigerator overnight before serving.
Freezer: Cooled sauce can be frozen up to 3 months. Thaw overnight in the refrigerator before serving.