First make the buttermilk. Measure out the milk. Add vinegar. Set aside for at least 5 minutes.
Preheat the oven to 375 degrees. Line the muffin tin with cupcake liners.
In a large bowl, add the oil, sugar, buttermilk, and eggs. Stir well.
Next, add the baking soda, cornmeal, flour, and salt. Stir well.
Add the corn. Stir well.
Scoop the buttermilk cornbread batter into the lined muffin tin about 3/4 full.
Bake for 30 minutes. Check the muffins with a toothpick after 30 minutes. If the toothpick does not come out clean, bake the muffins for another 2-3 minutes and check again. Repeat if needed.