To a large mixing bowl, add cornmeal, flour, salt, baking powder and baking soda. Mix well.

Add eggs, milk and onion. Stir until combined. Do not overmix.

Pour about 1/2 inch oil into a large cast iron skillet. (Alternately, fill a large cooking pot, Dutch oven or fryer with oil to about 3 inches.)

Place over medium heat and heat until oil reaches 355°F as measured on a candy thermometer.

Carefully drop a few dollops of hush puppy batter into hot oil with a large tablespoon or small to medium ice cream scoop. Do not crowd. Try to make them all of roughly equal size for perfect results.

Fry until golden brown, turning as needed.

Remove hush puppies with slotted spoon to a paper towel-covered plate to drain.

Repeat with remainder of batter.

Serve hot with tartar sauce or other dipping sauces.