1. use a 9″ standard Pyrex glass pie plate

for the crust

1. Place the first 4 ingredients in a medium bowl and whisk together.
2. Rub in the chilled butter cubes with your fingertips, until a few small lumps remain.
3. Stir in the buttermilk and knead gently until mixture forms into a dough, remove from bowl and wrap in plastic, chill for 1 hour.

for the heirloom tomato filling

1. Place tomato slices on a baking sheet lined with paper towels. Place another layer of paper towels on top of tomato slices.
2. Let stand for 30 minutes to remove some moisture.
3. Preheat the oven to 425F.
4. Roll out the dough between 2 layers of plastic wrap to a 11″ circle.
5. Remove the top layer of plastic wrap and gently flip dough over to place in the pie plate, carefully peel off the remaining plastic wrap.
6. Whisk the scallion, mayonnaise, basil, vinegar, sugar, salt and pepper in a small bowl.
7. Sprinkle the cornmeal evenly over the bottom of the crust.
8. Top with 1/2 cup of grated cheese.
9. Arrange 1/3 of tomato slices over cheese, slightly overlapping if needed.
10. Spread half of mayo mixture over the tomatoes.
11. Sprinkle with 3/4 cup of cheese, 1/2 of remaining tomatoes and remaining mayo mixture.
12. Sprinkle 3/4 cup of cheese over mayo mixture, then remaining tomato slices.
13. Sprinkle remaining cheese (about 1/2 cup) on top.
14. Fold the overhanging crust up and over the edges of the tomatoes.
15. Bake until pie crust is deep golden brown, about 35-40 minutes.
16. Tent pie with foil half way through baking time if the crust looks like it’s getting too dark.
17. Let pie cool on a metal rack for at least 1 hour before serving.