In a large bowl or in the bowl of an electric mixer, whisk together the whole wheat flour, cornmeal, and salt to evenly combine.
Pour in the olive oil and 1/4 cup water and mix with the hook attachment until the dough comes together in a ball with a tacky consistency-dry, but neither too crumbly nor too stiff.
Add 1 to 2 tablespoons more water if necessary to achieve this texture.
Alternatively, the dough can be mixed with a spoon, then kneaded by hand on a surface lightly sprinkled with flour.
Wrap the dough in plastic and refrigerate for 30 minutes or up to 3 days.
Preheat the oven to 450 degrees.
Divide the dough into 4 squares.
Lightly sprinkle a flat surface with flour and roll each square out to a thickness of about 1/8 inch.
Use a knife to cut out crackers into 2-by-1-inch rectangles.
Arrange the rectangles on baking sheets (it will be necessary to bake in batches) and bake until the crackers are crisp and the edges are dark brown, 8 to 10 minutes.
Store the crackers in an airtight container for up to 2 weeks.