Preheat the oven to 350 degrees.
Mix the cornmeal, flour, baking soda, salt, and sugar together. Set aside.
Mix the apple cider vinegar, milk, maple syrup, and oil together.
Make a well in the center of the dry ingredients, and add the wet mixture. Mix until combined and no flour is visible.
Pour the batter into either a 12 inch cast iron skillet or a 9x9 square baking pan.
Bake for 30-40 minutes, or until the top is lightly golden and a toothpick inserted into the center of the cornbread comes out clean.