Blueberry Pie Filling Without Cornstarch. 1 tablespoon freshly squeezed lemon juice. Bring to a boil over low heat;

In a small bowl, combine the flour, lemon zest, baking powder, salt, baking soda and remaining sugar; Just whisk together the filling ingredients. It’s one large bowl, one spoon, and you just pour it into a crust and bake.