In a bowl, combine the salmon, onion, salt and pepper. Stir in the egg, buttermilk, cornmeal and flour. Combine well. Heat about 1/4″ oil in the bottom of a med. size iron skillet over med. high heat. Drop spoonfuls of the salmon mixture into the hot oil and flatten out just a tad. Fry, in batches, about a minute per side or until golden brown. Drain on a paper sack or paper towel lined plate.