In a medium saucepan, combine the blueberries, sugar, lemon juice, and salt. Mash with a potato masher or wooden spoon until the berries have released their juice.

Cook over medium-high heat, stirring occasionally, until the mixture has thickened, 18-25 minutes. Transfer to containers and refrigerate for up to 1 month or freeze for up to 1 year

TIP: This recipe can also be made with two 10oz bags of frozen blueberries instead of fresh. Cook the frozen berries for 2-3 minutes before mashing, then reduce the total cooking time to 15-17 minutes.