Pulse flour, cornmeal, sugar, and salt in a food processor (about 3 times to combine). Then add the butter pieces, pulse about 8 times until the butter is incorporated, then slowly drizzle in the ice water and then process until everything is combined and the dough comes together in the food processor (about a minute).
Remove ingredients from the food processor and form a ball. Then out of that ball divide it into two other balls, then repeat that until you have 8 small balls. Flatten into discs.
Lay out a piece of plastic wrap, lay 8 discs on it, cover it with another piece of plastic wrap and put in the freezer for half an hour.
After half an hour lightly dust a board with flour, then roll out the discs and line tart forms (or free form them into crusts.)