In a large saucepan, saute the onion and red pepper in butter until tender. Add the milk. Bring to a boil. Gradually whisk in cornmeal; whisk constantly until thickened, about 5 minutes. Add the cheese, parsley, 1/2 teaspoon salt and pepper. Add 1 cup cornmeal mixture to the egg yolks; mix well. Return all to saucepan.
In a large bowl, beat egg whites, cream of tartar and remaining 1/2 teaspoon salt until stiff peaks form. Fold into the cornmeal mixture. Transfer to a greased 2-qt. souffle dish.