Whisk egg white until foamy. Whisk in the water and vanilla. Next, whisk in the flour and salt.
Slice the apples into 1/2-inch thick slices. Using varying sized cutters, cut “rings” out of apple slices, discarding smallest circle containing core.
Heat oil to 375 degrees. Preheat oven to 400 degrees.
Dip apple rings into batter and then place into the oil. Allow the apples to fry in small batches and turn frequently. Remove from the oil when golden brown and place on a paper towel. Sprinkle with cinnamon and sugar.
Transfer rings to a wire rack and place the wire rack on a baking sheet. Place in the oven for 5-10 minutes or until the rings turn crispy.
Drizzle the icing over the rings and serve warm. (To make the icing, simply combine all of the ingredients and stir until combined).