Prep the skewers: If using wooden skewers, soak them in water for at least 20–30 minutes to prevent burning. Metal skewers need no prep.
Make the marinade: In a large bowl, mix olive oil, lemon juice, garlic, cumin, coriander, sweet and smoked paprika, cinnamon, turmeric, cayenne, salt, black pepper, and chopped cilantro or parsley.
Season the lamb: Add lamb cubes to the bowl and toss until every piece is well coated. For best flavor, marinate 20–30 minutes at room temperature or up to 6 hours in the fridge.
Preheat the air fryer: Set to 400°F (200°C) for 3–5 minutes.
Preheating helps develop nice browning.
Assemble the skewers: Thread lamb pieces onto skewers, alternating with red onion and bell pepper if using. Don’t pack them too tightly; a little space promotes even cooking.
Air fry the first batch: Lightly oil the air fryer basket or use a perforated parchment liner rated for air fryers. Arrange skewers in a single layer with space between them.
Cook at 400°F (200°C) for 8–10 minutes, turning halfway.
Check doneness: For medium, aim for an internal temperature of about 140°F (60°C), understanding it will rise slightly as it rests. Add 1–2 minutes if you prefer more doneness.
Rest and finish: Transfer skewers to a plate and rest 3–5 minutes. Squeeze fresh lemon over the top and sprinkle with chopped herbs.
Make the yogurt sauce (optional): Stir yogurt, lemon juice, olive oil, grated garlic, salt, and herbs.
Adjust seasoning to taste.
Serve: Plate with yogurt sauce, warm pita or flatbread, a crisp cucumber-tomato salad, or couscous.