Heat the oven to 325 degrees F.

In the food processor or in a large bowl, stir together the flour, cornmeal, salt and sugar. Add the egg and mix well. Blend in enough of the milk to form a dough that will hold together in a cohesive ball.

On a floured surface or pastry cloth, roll into a rectangle about 3/8 inch thick. With a sharp knife, cut the dough into 1 1/2 x 3-inch rectangles. Place them on a lightly greased or parchment-lined baking sheet. Prick each cracker 2 or 3 times with the tines of a fork. Bake for 60 to 70 minutes, or until the crackers are thoroughly dry.

Cool on a rack. These crackers should be hard. If necessary, put them back in the oven for a few extra minutes.