Preheat oven to 400°F. Line muffin pan with liners or grease well with cooking spray.
Whisk together flour, cornmeal, sugar, salt, baking powder, and baking soda.
Add egg, buttermilk, and vegetable oil. Mix until combined.
Spoon batter into muffin cups, filling them just under 2/3's of the way full.
Bake for 12-15 minutes, until a toothpick inserted into the center comes out clean.