You're going to need an oven-proof skillet for this recipe. I highly recommend getting at least one cast iron pan. They aren't the cheapest but they last a lifetime and you can often find them at thrift stores and garage sales. We bought a small one at a church sale for C$0.50!
This cornbread freezes well if you wrap it in plastic and foil. Leftovers make great toast too!
Have all of your ingredients measured and ready to go before you start (mise en place).
Melt the butter in an oven-safe skillet over medium heat. Once the butter is melted, swirl the butter around the pan to coat the sides as well. Turn off the heat. While the butter is still hot, pour the sugar in and mix it into the butter until it is mostly melted.
Mix the vinegar into the milk, stir and set aside.
With the pan off the heat/hot element, crack the eggs into the pan and whisk them into the butter/sugar with a fork.
Mix the baking soda into the milk and vinegar mixture and immediately add it to the skillet. Mix again with a fork.
Sprinkle the cornmeal, flour and salt over the contents of the skillet. Mix it with a rubber/silicone spatula just enough so that you don't see any powdery bits - make sure to go around the outside and the bottom. Add the optional.canned mild green chilis and stir just so they're not in one clump.
Pop the skillet in the oven (middle rack) and bake for about 35 minutes. Insert a skewer or a toothpick in the centre of the pan. If it comes out clean, take the cornbread out of the oven. If it's a bit goopy, bake for another 5-10 minutes and check again.
Let it cool for a few minutes and run a knife around the inside of the pan to loosen the cornbread. Serve in wedges, with or without butter.