Preheat oven to 425°F. Combine non-dairy milk and vinegar and set aside. Mix cornmeal, flour, sugar or other sweetener, salt, baking powder, and baking soda in a separate large bowl. Add non-dairy milk mixture and oil. Stir until just blended. Spread batter evenly in a vegetable oil sprayed 9"×9" baking dish. Bake until top is golden brown, 25 to 30 minutes. Serve hot.