This gluten-free corn dog recipe uses buttermilk. I do not suggest substituting the buttermilk in this corn dog recipe if you don't have to. If you used homemade buttermilk, I would start with a smaller amount and add just enough to make the batter thick. If you get too much liquid, the batter will not stick to the hot dogs as well. The best way to get a thicker homemade dairy-free buttermilk is to mix 2 parts dairy-free milk and 1 part dairy-free greek-style yogurt.