4 cups fresh or frozen blueberries
2 cups granulated sugar
2 tablespoons lemon juice
1 tablespoon lemon zest, optional
1 packet fruit pectin, optional
Rinse the blueberries and remove stems
Mash the blueberries slightly in a large saucepan
Add the sugar and lemon juice
Add the lemon zest, if using
Stir over medium heat until the sugar dissolves
Bring the mixture to a boil
Add the pectin, if using, and boil according to package directions
Continue boiling until the mixture thickens
Test for doneness with a chilled plate
Remove from heat
Skim off any foam
Ladle into clean jars
Leave a small amount of headspace
Seal the jars
Cool completely
Refrigerate for immediate use or process in a water bath for shelf storage