In a medium saucepan, heat blueberries over medium heat until they release their juices & soften. (about 7-9 minutes)

In a separate bowl- whisk sugar, cornstarch, & salt.

Once your blueberries have cooked, pour in dry mixture & thoroughly combine.

Heat & stir constantly until mix thickens- 2-3 minutes.

Remove from heat & stir in lemon juice.

Transfer to glass jar & let cool in refrigerator.