1. Beat egg yolks with sugar until light and creamy.
2. Combine banana, salt, cake flour and potato flour, add to egg mixture.
3. Add a pinch of salt to the whites, and beat unitl stiff, fold into the banana mixture.
4. Fold nuts lightly into the batter, and pour into a lightly greased cake pan.
5. Bake at 325 degrees for 40-45 minutes or until light brown on top, remove from heat and cool on backing rack.
6. For the frosting combine egg white, sugar, salt and water in a double boiler, bring water to a boil and beat the frosting with a whisk until it thickens to desired consistancy.
7. Spread frosting on a completely cooled cake and serve.