For the filling: Stir the sugar, cornstarch, cinnamon, and salt together in a large bowl. Add the berries and mix gently with a rubber spatula until evenly coated; add the lemon zest and juice and mix to combine. Transfer the berry mixture to a 9-inch glass pie plate, place the pie plate on a rimmed baking sheet, and bake until the filling is hot and bubbling around the edges, about 25 minutes.
For the biscuit topping: Meanwhile, whisk the flour, cornmeal, 1/4 cup sugar, baking powder, baking soda, and salt in a large bowl to combine. Whisk the melted butter, buttermilk, and vanilla together in a small bowl. Mix the remaining 2 teaspoons sugar with the cinnamon in a second small bowl and set aside. One minute before the berries come out of the oven, add the wet ingredients to the dry ingredients; stir with a rubber spatula until just combined and no dry pockets remain.
To assemble and bake the cobbler: Remove the berries from the oven; increase the oven temperature to 425 degrees. Pinch off 8 equal pieces of biscuit dough and place them on the hot berry filling, spacing them at least 1/2 inch apart (they should not touch). Sprinkle each mound of dough with cinnamon sugar. Bake until the filling is bubbling and the biscuits are golden brown on top and cooked through, 15 to 18 minutes. Cool the cobbler on a wire rack 20 minutes and serve.
Variation: All-Season Blueberry Cobbler (with Frozen Blueberries)
Note:Thawed berries shed a lot of flavorful liquid that must be reduced to a syrup on the stovetop before baking.
Thaw 36 ounces (about 6 cups) frozen blueberries (preferably wild) in a colander set over a bowl to catch the juices. Transfer the juices (you should have about 1 cup) to a small saucepan; simmer over medium heat until syrupy and thick enough to coat the back of a spoon, about 10 minutes.
Follow the recipe for Blueberry Cobbler, mixing the syrup with the berries and other filling ingredients, increasing the baking time for the berry mixture to 30 minutes, and increasing the biscuit baking time to 20 to 22 minutes.
Adam Rapoport, editor in chief of Bon Appetit magazine and the website www.bonappetit.com, knows his way around a grill. He has edited an entire book on the subject: The Grilling Book: The Definitive Guide from Bon Appetit.