Combine flour, cornmeal, sugar, baking powder, and salt, and whisk until fully combined.
Add in your wet ingredients, egg, buttermilk, and melted butter. Mix until fully combined and then refrigerate for 20 minutes.
Meanwhile prep your hot dogs, cut each hot dog into 3 equal pieces, and toss to coat lightly in additional flour.
Heat about 2 inches of oil to 350 degrees in a heavy bottom pan.
Dip your hot dogs in your chilled corn dog batter, I like to use a skewer to dip them, but you can use a fork. Fully coat the dog and allow the excess batter to drip off.
Fry for 3-5 minutes or until golden brown.
Place on a wire rack or a paper towel to cool down.
Notes
If you don't have buttermilk, you can always substitute regular milk with a splash of white vinegar.