In a small saucepan, stir together sugar, 3 tablespoons water, and cornstarch until smooth. Bring to boil over high heat. Reduce heat to maintain a low boil, and cook, stirring frequently, for 1 minute. Stir in blueberries and return mixture to a boil. Reduce heat, and simmer until some of the blueberries have popped, 1 to 2 minutes. Remove from heat. Add lemon zest and juice, stirring until incorporated.
Recipe by TeaTime Magazine at https://teatimemagazine.com/blueberry-blintzes-recipe/