In a medium bowl, combine the peaches, lemon juice, vanilla, salt and 2 tbsp sugar. Let stand for 15 minutes.
Drain peaches, reserving 1 tbsp liquid. Whisk cornstarch and remaining 1 tbsp sugar into reserved liquid. Add to peaches and stir.
Cut each pastry sheet into 4 equal pieces by cutting a large “X”. Divide peach filling in the centres of the resulting 8 pieces.
Brush edges of pie crust with water, fold over to form triangles and crimp with a fork to seal. Use the fork to poke holes in the top of each pastry.
Select AIR FRY, then adjust the temperature to 182°C and the time to 10 minutes, then touch START.
When the display indicates “Add Food” place pastries in a single layer on the cooking tray (you may need to work in batches).
When the display indicates “Turn Food” do nothing.
When the Air Fry program is complete, remove the turnovers and sprinkle with powdered sugar.