Prep the potatoes: Wash and dry them. Peel if you like, but the skin adds flavor and texture. Cut into even 1/2-inch cubes so they cook uniformly.
Soak briefly: Add the cubes to a bowl of cold water and soak for 10 minutes. This pulls off extra starch for crispier edges.
Dry well: Drain and pat the potatoes dry with a clean towel. Moisture is the enemy of crispiness, so take an extra minute here.
Season: In a large bowl, toss potatoes with oil, paprika, garlic powder, onion powder, herbs, red pepper flakes, salt, and black pepper. If using bell pepper and onion, toss those in too.
Preheat the air fryer: Set to 400°F (200°C) for 3 minutes. Preheating helps the potatoes start crisping right away.
Air fry in a single layer: Add potatoes to the basket in a mostly even layer. A little overlap is fine, but avoid overcrowding. Cook for 10 minutes.
Shake and continue: Shake the basket or toss with tongs. Cook another 8–12 minutes, shaking every 4–5 minutes, until crispy and golden. Total time is usually 18–22 minutes.
Taste and finish: Check seasoning and add more salt if needed. Garnish with chopped parsley or chives. Serve hot.