Combine Ingredients: In a medium-sized saucepan, combine the blueberries, sugar, water, and lemon juice. Stir to combine.
Simmer: Bring the mixture to a simmer over medium heat, stirring occasionally.
Mash the Blueberries: Once the mixture begins to simmer, reduce the heat to low. Use a potato masher or the back of a spoon to mash the blueberries, releasing their juices and flavor.
Strain (Optional): For a smoother syrup, strain the mixture through a fine mesh sieve to remove the blueberry skins. Skip this step if you prefer a textured syrup.
Reduce and Thicken: Return the syrup to the pot and continue simmering for another 5-10 minutes, or until it reaches your desired consistency.
Add Vanilla Extract: Once thickened, remove the syrup from the heat and stir in the vanilla extract (if using).
Cool and Store: Allow the syrup to cool to room temperature, then transfer it to an airtight container or jar for storage. Store in the refrigerator for up to two weeks.
