Sift together the flour, salt, baking soda and sugar into a mixing bowl.
Combine the egg yolk with the sour cream and stir into the flour mixture.
Beat in the melted butter or vegetable oil.
Set aside and allow to stand for at least an hour.
Beat the egg white until stiff and fold into the batter.
Fill a hot lightly oiled waffle iron two-thirds full with the batter and cook until steam no longer appears.