Step 1: Combine blueberries, sugar, and water in a medium saucepan. Add the fresh lemon juice and stir gently to combine all ingredients.
Step 2: Place the saucepan over medium heat. Bring the mixture to a gentle simmer, stirring occasionally to dissolve the sugar. Once simmering, reduce the heat to low.
Step 3: Allow the mixture to simmer for 10-15 minutes, or until the blueberries have softened and begun to burst. As they soften, gently mash them with a potato masher or the back of a fork. This helps release their juices and flavor.
Step 4: Continue to simmer for another 5-10 minutes, stirring occasionally, until the syrup has thickened slightly. The consistency will be looser than you might expect at this stage, as it will thicken further as it cools.
Step 5: Carefully place a fine-mesh sieve over a heatproof bowl. Pour the blueberry mixture through the sieve, using a spatula or the back of a spoon to press against the solids to extract as much liquid and pulp as possible. Discard the remaining solids.
Step 6: Transfer the strained blueberry syrup into a clean, airtight container. Allow it to cool completely at room temperature before refrigerating.