Preheat the oven to 425 degrees F. For the shortcakes: Place the flour, cornmeal, sugar, baking powder, salt and butter cubes in the food processor. Pulse until the mixture looks crumbly. Then pulse in the eggs and buttermilk, until the dough forms a ball. Wrap the dough in plastic and refrigerate.
Prep the strawberries and place in a deep-dish 12 inch cast iron skillet. Add in the sugar, lemon zest, corn starch, vanilla and salt. Place over a burner and set to medium-high. Simmer for 5-7 minutes to melt the sugar and start breaking down the strawberries. Stir occasionally.
Meanwhile, flour a clean work surface. Press the cold shortcake dough out into a rectangle, 1 inch thick. Fold over once, then press out again into a rectangle, 1 inch thick. Use a 2 or 2-1/2 inch round cookie cutter to cut 10-12 shortcakes. Brush the tops of the shortcakes with extra buttermilk and sprinkle with sugar. (Work fast so the dough is still cold when placed in the oven.)
Arrange the shortcakes evenly over the surface of the simmering strawberries and immediately move the skillet to the oven. Bake for 20 minutes, until the shortcake tops are puffed and golden brown. Serve warm, with a dollop of whipped cream or vanilla ice cream.
Notes
NOTE: If you do not have a deep-dish skillet, pour the simmered strawberries into a 12-inch ceramic baking dish and top with the shortcakes before baking. If you use a shallow skillet, the strawberries juices will bubble over the edges and burn in the bottom of the oven.