Preheat your air fryer to 400℉.
Wash and dry the plantains. Using a knife, cut off the ends of the plantain and score through the skin along the length of the plantain, being careful that you don’t cut the flesh.
Using your fingers, peel the skin away from the flesh of the plantain.
Cut the plantain into 1-inch thick chunks.
Transfer the chunks to the air fryer basket, and spray them with olive oil spray.
Air fry for 3 minutes, turn plantain over, and air fry for three more minutes.
Meanwhile, add the cooking oil, garlic powder, and salt to a bowl and mix.
Remove the plantain chunks from the air fryer, and place them on a cutting board. Smash them with the bottom of a mason jar or a mug.
Dip a pastry brush into the oil mixture, and brush both sides of the smashed plantains.
Return the plantain pieces to the air fryer basket.
Air fry for 4 minutes, flip the tostones, and air fry them for another 4 minutes or until they are golden brown and crispy on the edges.