In a medium to a large bowl, combine egg yolk, wine, sugar, and salt. Beat until it gets foamy.
Add flour, then mix.
Add melted butter and mix. Set aside for at least 15 minutes.
In the meantime, core, peel, and slice the apples into rounds (about ¼ inch thick). Squeeze some lemon juice on the sliced apples to avoid discoloration.
Beat the egg white until stiff. Fold the beaten egg white into the batter.
Using a frying pan, heat the vegetable oil over medium-high heat.
Once the oil is ready, adjust the heat into medium.
Dip a slice of the apple into the batter and start frying.
Once the fritters are slightly brown on both sides, remove them from the pan and place them on top of a paper towel (to absorb excess oil).
Serve these fried apples with vanilla sauce or sprinkle with cinnamon and sugar, if desired.