Heat oil 375 F (190 C). You can use a deep fryer, or a heavy pan. If not using a deep fryer, use a deep, heavy pot, filled to at least 3" deep.
Dry the hot dogs off with napkins WELL. Dust with a little masa flour, set aside
Combine all dry ingredients - including seasonings, if using - whisking to combine.
In a separate bowl, whisk eggs, buttermilk, and melted butter together. Combine wet and dry ingredients, mixing until well combined and relatively smooth.
Transfer batter to a tall glass, cover with plastic film, allow to sit for 10 minutes.
If using skewers, stick them into hotdogs, making sure they go in to about halfway up the length of the hotdog.
Gently dip hotdogs in the batter one at a time, slowly removing from the batter and allowing excess to drip off.
Carefully transfer dipped hot dogs to heated oil. Fry a few at a time - turning every few minutes - until golden brown.
As corndogs are cooked, use a (metal!) slotted spoon to transfer them from the oil, to a pan lined with paper towels.
Serve hot, with mustard and/or ketchup for dipping.