In a medium bowl, combine the diced apples, lemon juice, cinnamon, brown sugar, and vanilla extract. Mix well until the apples are fully coated.
Place a tortilla flat on a clean surface and add about 2 tablespoons of the apple mixture at one end.
Roll the tortilla tightly, starting from the end with the filling, to form a taquito. Repeat with the remaining tortillas and filling.
Brush each taquito lightly with melted butter and then place them seam-side down in the air fryer basket. Make sure they are not overcrowded; you may need to do this in batches.
Spray the taquitos with cooking spray to help them crisp up during cooking.
Air fry at 375°F (190°C) for 8-10 minutes, flipping them halfway through, until they are golden brown and crispy.
Once cooked, remove the taquitos from the air fryer and let them cool for a couple of minutes.
For a finishing touch, sprinkle a mixture of cinnamon and sugar over the warm taquitos.
Notes
Serve warm for the best flavor. Adjust cinnamon and sugar to taste.