Step 1

Mix flour, cornmeal and 1/2 teaspoon salt in a large bowl or food processor. Cut in butter using a pastry blender, two knives or by pulsing in the food processor until the butter forms pebble-size pieces with the flour. Add water, 1 tablespoon at a time, until the dough is evenly moist (but not wet) and is just starting to clump together, being careful not to overmix. Pat the dough into a 5-by-7-inch rectangle and wrap in plastic. Refrigerate for at least 1 hour and up to 2 days.

Step 2

Preheat oven to 400 degrees F. Let the dough stand at room temperature for about 15 minutes before rolling.

Step 3

Roll the dough on a lightly floured surface into a 12-by-17-inch rectangle. Check for sticking frequently and dust with more flour if necessary. Transfer the dough to an ungreased 10-by-15-inch jelly roll pan and press into the bottom and up the sides. Prick with a fork several times; line with parchment paper and cover with pie weights (or dry beans).

Step 4

Bake the crust for 15 minutes. Remove the paper and weights and continue to bake until the crust is lightly browned, 8 to 12 minutes more.

Step 5

Combine oil, herbs, garlic and the remaining pinch of salt in a small bowl. Brush the mixture over the crust. Arrange tomato slices on top and scatter with burrata, more herbs and flaky salt, if desired.