Preheat oven to 325 degrees. Grease and flour a fluted pan. Mix the flour, baking soda and salt in a large bowl. Add the chopped apples and the nuts to the flour mixture and stir. In a separate bowl combine the oil, the beaten eggs, the vanilla extract and the sugar and then add this to the flour mixture, stirring until all ingredients are moistened. Pour this batter into the prepared tube pan and bake for 1 1/2 hours. Cool the cake in the pan, then turn it out onto a cake plate. Sprinkle with a little powdered sugar, if desired.