Preheat oven to 350ºF. Grease and flour a 10-inch tube pan or bundt cake pan.
Combine the flour, salt, baking powder, and sugar in a large bowl. Stir in the apple sauce, eggs, orange juice and vanilla; mix well. Add apple pie filling and stir. Pour batter evenly into the prepared pan.
Bake uncovered for 1 hour. Let cool for 15 minutes.
Invert onto serving plate and cool. Drizzle with citrus glaze if desired.
In a medium bowl, beat powdered sugar and orange juice for 1 minute or until smooth. Add additional orange juice by the teaspoon if needed for desired consistency.