Line a large plate with a double layer of paper towels and set it near the stove for draining the fried hush puppies.

In a large bowl, whisk together 1 1/2 cups fine cornmeal, 1/2 cup all-purpose flour, 1 1/4 teaspoons kosher salt, 2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/4 teaspoon Cajun or Creole seasoning, 1/2 teaspoon garlic powder, and 3/4 teaspoon granulated sugar until evenly combined.

Grate 1/2 small yellow onion (about 1/4 cup) directly into the dry mixture. Add 1 large egg and 1 cup buttermilk, then stir gently until just combined—do not overmix. The batter will be thick.

Cover the bowl and let the batter rest for 15 minutes at room temperature.

While the batter rests, pour 4 cups canola oil or vegetable oil into a deep pot or Dutch oven to a depth of about 1 1/2 inches. Heat the oil over medium-high heat until it reaches 365°F (use a deep-fry thermometer).

After the batter has rested, reduce the heat slightly if the oil is above 365°F; maintain the oil temperature at about 365°F while frying.

Use a small ice cream scoop or two spoons to form rounded dollops of batter about 2 tablespoons each. Carefully drop the dollops into the hot oil, frying in batches and avoiding crowding the pot so pieces can move and brown evenly.

Fry the hush puppies, turning gently with a slotted spoon as needed, until they are golden brown on all sides, about 3 to 4 minutes per batch. Monitor the oil temperature and adjust the heat to keep it near 365°F.

Transfer the fried hush puppies to the prepared paper towel–lined plate to drain for a minute or two.

Serve the hush puppies hot for best taste and texture.