Preheat oven to 400 degrees. Grease a 9 x 13 inch baking pan.
Whisk together the milk and the vinegar. Let sit for five minutes.
In a large bowl whisk together the flour, cornmeal, sugar, baking powder, baking soda, and salt.
In another bowl whisk together the milk + vinegar, eggs, and oil.
Gently fold the wet ingredients into the dry ingredients until just combined.
Pour the batter into the prepared pan. Bake 20 to 30 minutes. At the end of the baking time, the center should be puffed up and bounce back when you push down on it gently. The edges will be golden and a toothpick inserted into the center of the bread will come out clean.