In another skillet, scramble and fry sausage and onion together till sausage is browned (drain grease).
In a large bowl, combine well the eggs, cornmeal mix, corn, sour cream, milk and oil.
Using greased iron skillet, pour half of the cornmeal mixture into the skillet and then sprinkle the sausage mixture over the cornmeal batter. Sprinkle the cheese over the sausage. Then pour the remaining half of the cornmeal mixture over all that.
Bake for 35 to 40 minutes at 425°. Let stand 10 minutes and enjoy.