Preheat oven to 165 degrees C. Grease a 23cm ring tin or equivalent sized cake tin..
Beat the egg yolks into a mixing bowl with an electric mixer until frothy. Gradually add the sugar until completely incorporated. Beat in the orange juice, lemon zest and orange zest.
Sift the potato flour and matzo meal together in a bowl then gently stir into the egg yolk mixture.
Beat the egg whites in a bowl with the salt using an electric mixer on high speed until stiff and shiny. Use a rubber spatula to fold 1/3 of the beaten egg whites into the egg yolk mixture. Gently run the spatula through the centre of the mixture then around the sides of the bowl, repeating until fully incorporated. Add the remaining egg whites, folding until just incorporated. Gently pour the batter into the prepared cake tin.
Bake in the preheated oven until the cake is set and lightly browned; about 1 hour. Remove from oven, invert the cake tin and let cool completely before removing the cake from the cake tin.