1. Add the cubed potatoes to a large pot filled with water over medium-high heat on the stove. Bring the pot of water to a boil, then reduce it to a simmer for 5-6 minutes or until the potatoes are slightly firmer than fork-tender. Drain the potatoes completely and spread them out on a baking sheet to allow them to cool.
2. Preheat the air fryer to 350 F. Drizzle the potatoes with the melted butter, sea salt and paprika and toss to coat. Add the potatoes to the air fryer in a single layer. If you’re unable to add them all, you’ll have to air fry the potatoes in batches. Cook the potatoes for 7-8 minutes. Open the lid, shake the potatoes, add the onions and cook for another 6-7 minutes or until fork-tender and soft, and crispy on the outside. Serve immediately.

Leftovers will last for 4-5 days in the fridge. Reheat them in the oven at 300 F for 10 minutes or in a skillet on the stove, until crispy again.