Sift flour with salt, baking powder, sugar and baking soda. Beat egg yolks with buttermilk and add to dry ingredients, stirring briefly but without making batter perfectly smooth. Add corn oil and butter and stir again. Beat egg whites until stiff and fold into batter. Drop approximately 4 Tbs. Batter on hot waffle iron and sprinkle some chopped pecans on top. Bake until done (4-5 minutes in an electric waffle iron). Note: Make certain that the waffle iron is very hot before making each waffle. You may also need to add a bit more buttermilk if the batter seems too thick; a thin batter makes a tender waffle.