Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch Bundt or tube pan. In a medium bowl, combine the diced apples, 1 tablespoon white sugar and 1 teaspoon cinnamon; set aside. Sift together the flour, baking powder and salt; set aside.
In a large bowl, combine 2 cups white sugar, oil, orange juice, vanilla and eggs. Beat at high speed until smooth. Stir in flour mixture. Fold in chopped walnuts.
Pour 1/3 of the batter into prepared pan. Sprinkle with 1/2 of the apple mixture. Alternate layers of batter and filling, ending with batter.
Bake in preheated oven for 55 to 60 minutes, or until the top springs back when lightly touched. Let cool in pan for 10 minutes, then turn out onto a wire rack and cool completely. Sprinkle with confectioners' sugar.