Fried Green Apples

Prepare the Batter: In a medium bowl, whisk together the flour, milk, vanilla extract, egg, and sugar until smooth. Set aside to rest while preparing the apples.
Slice the Apples: Peel apples using a potato peeler or knife. Slice each apple into 5 to 6 rings, about ¼ inch thick. Core each ring using an apple corer or a small cookie cutter to remove the center (it will look like a donut).
Heat the Oil: In a skillet (cast iron works great), heat about 1 to 1½ inches of vegetable oil to 360°F. Use a thermometer if you have one to keep the temperature steady.
Dip and Fry: Dip each apple ring into the batter, letting the excess drip off slightly. Then, carefully lower into the hot oil using a fork through the center hole. Fry until golden brown, about 1 to 2 minutes per side.
Add Topping: Remove rings from oil and immediately sprinkle with the cinnamon-sugar mixture. This helps the sugar adhere to the hot batter.
Drain and Serve: Place fried apple rings on a paper towel-lined plate to absorb excess oil. Serve warm, with an optional dusting of powdered sugar.