Step 1

Make the crust and topping: Preheat the oven to 350°F. In a medium bowl, whisk together the flour, cornmeal, confectioners’ sugar, brown sugar, baking powder, and salt. Add the melted butter, then use your hands or a wooden spoon to combine the ingredients until a coarse little dough comes together, with no obviously dry spots.

Step 2

Press three-quarters of the cornmeal mixture into a 9-inch tart pan with a removable bottom. (Alternatively, use a 9-inch round cake pan, 9-inch springform pan, or an 8x8-inch pan lined with parchment.) Make sure the mixture is evenly pressed on the bottom and about ½ inch up the sides. (Using something like the bottom of a measuring cup will be helpful.) Place the tart shell on a sheet pan and pop it (and the remaining cornmeal mixture) into the fridge while you prepare the filling.

Step 3

Make the filling: In a medium bowl, toss the blueberries, brown sugar, vinegar, flour, and salt together. Pour the fruit into the crust. Crumble the remaining cornmeal mixture over the blueberries, pressing the mixture together into large clumps as you go, as you would with a crisp or coffeecake topping (it won’t cover the top entirely; just a nice sporadic covering, to allow the blueberries and their juices to poke through).

Step 4

Bake until the filling is bubbling, and the crust and top are nicely browned, 50 to 55 minutes. Let the tart cool completely before serving.