Preheat the oven: Set your oven to 350°F (175°C) and place the rack in the center.
Prepare the crust: Roll out your pie crust and press it into a 9-inch pie plate. Crimp the edges and set aside.
Par-bake the crust (optional): For a crisp bottom, bake the crust for 10 minutes, then let cool while you mix the filling.
Mix dry ingredients: In a large bowl, whisk together the sugar, cornmeal, flour, and salt until evenly combined.
Add melted butter: Pour in the melted butter and mix until the dry ingredients are moistened and smooth.
Add eggs and liquid: Beat in the eggs, one at a time, followed by the milk, vanilla extract, and vinegar or lemon juice if using.
Stir until smooth: Mix everything together until the filling is thick, creamy, and well blended.
Pour into crust: Pour the filling into your prepared pie crust, smoothing the top with a spatula.
Bake until set: Bake for 45 to 50 minutes, or until the top is golden brown and the center is just slightly jiggly.
Cool completely: Let the pie cool on a wire rack for at least 2 hours before slicing.
Dust and serve: Sprinkle with powdered sugar if desired, slice, and enjoy.