Scrub the potatoes clean under cold running water, cut them into small cubes, add to a colander and rinse with cold water. Drain and pat dry with a kitchen paper towel and transfer into a large mixing bowl.
Preheat the air fryer at 190/375F for 3 minutes
To the bowl of the potatoes, sprinkle the lemon pepper seasoning, garlic granules, and some salt, drizzle 1 ½ Tablespoons of olive oil and toss everything together until coated.
Transfer the potatoes into the air fryer basket or tray, making sure not to overcrowd it. Cook for 12 minutes at 190C/375F, shaking the basket halfway through the cooking time.
In the meantime peel and roughly chop the onions, and add it to the same bowl you used for the potatoes. Season the onions with the reserved lemon pepper, and salt, drizzle the rest of the olive oil and stir so that the onions are well coated.
After 12 minutes, remove the air fryer basket or tray. Add in the chopped onions and give everything a good mix. Spread the potatoes and onions out evenly in the basket/tray and cook for a further 5-7 minutes or until nicely browned and crispy. The onions should be soft, translucent, and slightly caramelized at this point too.
Serve immediately as desired. Enjoy!