In a medium saucepan, add the blueberries, sugar, water, and salt. Stir gently to combine. Set the lemon juice aside for later.
Turn the heat to high and bring the mixture to a boil.
Once boiling, reduce the heat to medium-low. Let it simmer for 10 minutes, stirring occasionally. The blueberries will begin to break down and the syrup will turn dark purple in color.
Remove the saucepan from the heat. Carefully strain the syrup into a clean bowl or jar using a fine mesh strainer. Use a spatula to press out all the liquid from the mashed berries.
Pour in the lemon juice and stir to combine.
Let the syrup cool at room temperature for at least an hour. Then pour it into a syrup bottle or mason jar, seal with a lid, and store in the fridge for up to 3 weeks.
Don’t toss the leftover fruit! Store the blueberries in a separate container in the fridge. They make a delicious topping for yogurt, oatmeal, pancakes, waffles, French toast, ice cream, or even stirred into a mocktail for added texture and flavor.