Alternate: single portion (5 hush puppies):
Stir cornmeal, flour, sugar, baking powder, salt, and cayenne in a medium bowl. Add onion, buttermilk, melted butter, hot sauce, and scallions (if using), and then stir until just combined.
Pour oil into a heavy duty pot to 2 inches deep. Heat over medium high heat until temperature reaches 375°F. Working in batches, gently roll dough into golf ball-sized balls and carefully lower into hot oil using a slotted spoon. Take care not to crowd pot. Fry until golden brown and cooked through, turning with wooden spoon for even browning, 2 to 3 minutes.