Preheat the oven to 375 degrees Fahrenheit.
Whisk the cornmeal, flour, and salt together in a large bowl.
Whisk the egg, whey or buttermilk, and oil together in a small bowl, then stir into the dry ingredients to form a moist dough.
Cut a sheet of parchment paper and a sheet of waxed paper large enough to cover a standard baking sheet.
Turn the dough out onto the sheet of parchment paper and form it into a rough rectangle with your hands. Cover with the sheet of waxed paper and roll into a paper-thin sheet of dough with a rolling pin. If any dough starts to squeeze out from under the waxed paper, gather up the excess, place it back on an exposed corner of the parchment paper, and re-roll until you've maximized the space.
Peel the waxed paper off the dough and transfer the parchment paper to the baking sheet. Score the dough with a pizza or pastry cutter, marking a grid of 1/2-inch by 1 1/2-inch strips. You don't have to separate each little cracker; they'll break apart easily when they're fully baked.
Bake for 18-20 minutes. Transfer the parchment paper to a cooling rack and break the crackers apart as soon as they're cool enough to touch. Cool completely before serving (if possible; the cook always needs to test a few for quality control, right?).