In a mixing bowl, combine cornmeal, flour, baking powder, and salt, stirring until well blended. Add in the chopped onion and gradually pour in cold water, mixing until a thick batter forms, resembling a pancake mix. Let the batter sit for about 5 minutes to thicken slightly while you prepare for frying.

In a deep, heavy-bottomed pan or a deep fryer, pour enough oil to submerge the hushpuppies about 2 inches deep. Heat the oil over medium-high heat until it reaches 350°F (175°C), using a thermometer for precision.

Once the oil is hot, carefully drop tablespoon-sized scoops of batter into the oil, frying them in small batches to prevent overcrowding. Fry each batch for about 3-4 minutes or until they turn a rich golden brown, turning halfway to ensure even cooking.

Using a slotted spoon, remove the fried hushpuppies from the oil and place them on a plate lined with paper towels to drain excess oil. Allow them to cool slightly; they should be crispy on the outside and tender on the inside.