Preheat the oven to 325ºF, with a rack in the middle of the oven. Grease a 12-cup fluted tube pan (Bundt pan).
In a bowl, sift together the flour, salt, baking soda and cinnamon. Stir in the dates, nuts and sugar.
In a large mixer bowl, beat the eggs, egg whites, oil, applesauce and vanilla until well blended.
Peel, core and chop the apples into dices, sprinkling with lemon juice as you cut them (to keep them from turning brown). Stir the flour mixture into the eggs. The batter will be very thick. Stir in the apples.
Spoon the batter into the prepared pan and bake for 65 to 75 minutes or until a toothpick inserted into the center of the cake comes out clean with no moist crumbs attached.
Cool on a rack for 20 minutes and then invert.The cake can be made 2 days in advance or frozen for up to 3 months.