.5 cup blueberries
.5 cup water (warm)
.5 cup sugar
.5 tsp lemon juice
Combine blueberries, water, and sugar in a small saucepan. Heat with low heat until sugar is dissolved, about 5 minutes. Increase heat to medium and bring to a gentle boil, stirring often, until syrup is thickened, about 20 minutes.
Whisk lemon juice into syrup; serve immediately or cool.