Preheat oven to 350°. Line bottom only of tube pan with waxed paper.
Combine almond flour, potato starch and matzoh cake meal and whisk well to combine. If it seems lumpy, sift and remove any lumps that can't be pressed through sifter. Set aside
In stand mixer with paddle beater, beat egg yolks, sugar and salt at medium speed until light colored. Turn speed to low and add orange juice, zest and orange oil (if using). Scrape down bowl and beater.
Add almond flour mixture and mix on low speed for a moment, increasing to medium and blend thoroughly. Scrape down bowl and beater and mix again briefly to combine. Remove bowl and beater from mixer; scrape down beater and fold through mixture to incorporate. You're done with the paddle beater.
In stand mixer using whisk attachment, beat eggwhites on low to medium speed until frothy. Increase speed to high and whisk until stiff but not dry peaks form.
Gently stir ¼ of whites into egg yolk mixture, lightening them. Gently fold in remaining whites until no streaks remain. Scrape around bowl to ensure all batter is completely combined.
Transfer batter to lined tube pan, making sure to not get batter on the tube or sides higher than the level of the batter. Bake approximately 45-50 minutes until a tester inserted half way between side and tube comes out clean. Immediately invert pan, either using the pans 'feet' or on the neck of a wine bottle. Allow to cool completely, approximately 2 hours.
When cake is cool, carefully run a thin knife or metal icing spatula around the edges of the cake pan. Invert cake onto the serving tray and remove outer pan. Carefully run the knife between the pan bottom and cake, allowing cake to drop onto serving plate. Remove waxed paper. Serve with mixed berry sauce.