In a large bowl, combine the diced apples, flour, granulated sugar, baking powder, baking soda, cinnamon, and salt. Mix well to coat the apples with the dry ingredients.
In a separate bowl, whisk together the egg, milk, and vanilla extract until smooth. Pour this mixture into the dry ingredients and stir until just combined. Do not overmix; it’s okay if there are a few lumps.
In a deep skillet or pot, heat about 2 inches of vegetable oil over medium heat until it reaches 350°F.
Using a small cookie scoop or tablespoon, carefully drop spoonfuls of the batter into the hot oil. Fry in batches, making sure not to overcrowd the pan. Cook for about 2-3 minutes on each side or until golden brown.
Remove the fritter bites with a slotted spoon and drain on paper towels. While still warm, dust with powdered sugar.
Serve immediately for the best flavor and texture.