Preheat the air fryer to 400°F (205°C) for 3 minutes.

Starting hot helps the skin begin rendering immediately instead of steaming. • Air fryer is hot when you open the basket and feel a wave of heat • Hot, dry heat when the basket opens

Pat the chicken thighs very dry with paper towels, especially the skin side.

Wet skin steams. Dry skin crisps. • No visible moisture on the skin • Skin goes from slick to tacky

In a small bowl, mix kosher salt (1¼ tsp), baking powder (½ tsp), pepper, garlic powder (1 tsp), and smoked paprika (1 tsp).

Baking powder is the crisp-skin lever—use a small, measured amount. • Evenly blended seasoning with no baking powder clumps • Smoky paprika aroma

Lightly rub the thighs with neutral oil (1 tsp), then season all over with the spice mix, focusing on the skin side.

Oil helps spices adhere and improves browning, but keep it light—too much oil can soften crisping. • Skin looks evenly dusted, not pasty • Spices bloom slightly as they hit the oiled skin

Place thighs in the air fryer basket skin-side up, leaving space between pieces (cook in batches if needed).

Crowding traps steam and kills crispness—space is part of the recipe. • Gaps between pieces, skin fully exposed

Cook at 400°F (205°C) for 18 minutes. Then flip and cook 4-7 minutes more, until the thickest part hits 175-185°F (79-85°C).

Skin-side up first maximizes crisping; the brief flip finishes the underside without sacrificing the top. • Skin is deep golden-brown with blistered spots • Frying-like sizzling, then a quieter steady roast sound

Rest 5 minutes before serving. Squeeze lemon over the top if using.

Resting prevents the first cut from dumping juices onto the board. • Juices stop aggressively bubbling at the surface • Crisp skin crackles when tapped