Dice the potatoes into ½-inch cubes and cut the steak into 1-inch pieces. Dice the onion and bell pepper. Pat the steak dry with paper towels.
In a medium bowl, toss the steak with 1 tablespoon olive oil, the garlic powder, smoked paprika, ½ teaspoon salt, and ¼ teaspoon pepper.
In a separate bowl, toss the potatoes with the remaining 1 tablespoon olive oil, ½ teaspoon salt, and ¼ teaspoon pepper.
Preheat the air fryer to 400°F (200°C) for 5 minutes.
Add the potatoes to the air fryer basket in a single layer. Cook at 400°F for 10 to 12 minutes, shaking the basket halfway through, until golden and crisp at the edges.
Add the steak, onion, and bell pepper on top of the potatoes. Cook at 400°F for 8 to 10 minutes, shaking once or twice, until the steak reaches your desired doneness and the vegetables are tender. Pull at 130°F for medium-rare.
Let the steak rest 3 minutes. Garnish with fresh parsley and serve hot.