In medium bowl, whisk together cornmeal, white rice flour, granulated sugar, baking powder, salt, baking soda, chipotle powder (if using), and xanthan gum.

In a medium bowl, whisk together onion, garlic, milk, and egg. Pour wet ingredients into dry ingredients and stir together until smooth but some lumps remain.

Heat oil in a Dutch oven over high heat to 350°F and adjust flame to maintain temperature. Line a rimmed baking sheet with paper towels.

Drop batter, about 2 teaspoons at a time into hot oil until you have a dozen hush puppies. Fry for two minutes and then turn the hush puppies. Fry until deep golden brown, about 2 minutes longer. Remove hush puppies from the oil with a skimmer. Transfer to prepared baking sheet. Repeat with remaining batter. Serve warm.