Mix dry and wet ingredients:
In a large bowl, combine flour, baking powder, sugar, and salt with a whisk. Separately, blend yogurt, egg, and vanilla. Pour the wet mixture into the dry and stir until barely combined; avoid overworking the batter.Fill donut pan:
Grease a donut pan (silicone or metal) that fits inside your air fryer. Fill each mold about 3/4 full with batter using a spoon.Air fry donuts:
Set the pan in the air fryer basket. Cook at 320°F (160°C) for 8–10 minutes, until the donuts are golden and bounce back when gently pressed.Cool and add toppings:
Take the pan out of the air fryer, allow donuts to cool a bit, then finish with optional toppings like glaze, powdered sugar, or cinnamon-sugar.