Cut the apples into ½ cm thick slices, removing the core.
Mix the rum with the sugar into a bowl.
Add the apple slices and mix gently, to avoid breaking them.
Leave for 30 minutes to infuse, mixing from time to time.
In another bowl, mix the flour with the baking powder.
Add a pinch of salt, a little bit of water and the egg yolk,to form a batter.
In a different bowl, mix the egg white until stiff.
Gently fold the egg white into the batter.
Heat some oil in a frying pan.
Pass each apple slice into the batter, then fry in the oil until golden brown.
Once done, take each slice out and drain on a kitchen towel.
Serve either hot or cold, with more sugar sprinkled on top.