Preheat the air fryer. Set it to 380°F (193°C). A preheated basket helps brown the meatballs right away.
Mix the aromatics. In a large bowl, combine grated onion (and its juices), garlic, parsley, dill, oregano, lemon zest, salt, and pepper.
Add the binders. Stir in the egg, breadcrumbs, and 1 tablespoon olive oil until evenly moistened. The mixture should look like soft, seasoned crumbs.
Fold in turkey and feta. Add the ground turkey and crumbled feta.
Gently mix with your hands or a spatula until just combined. Do not overmix or the meatballs will turn dense.
Shape the meatballs. Scoop about 2 tablespoons per meatball and roll gently into balls (around golf-ball size). You should get 16–18 meatballs. Lightly oil your hands if the mixture is sticky.
Oil the basket. Mist or brush the air fryer basket with olive oil to reduce sticking.
Place meatballs in a single layer with space between them. Work in batches if needed.
Air fry. Cook for 10–12 minutes, shaking the basket or turning the meatballs halfway through. They’re done when browned and the internal temperature reaches 165°F (74°C).
Rest briefly. Let the meatballs sit for 3–5 minutes to lock in juices.
Squeeze a little lemon over the top for extra brightness.
Serve. Pair with tzatziki, cucumber-tomato salad, warm pita or rice, olives, and a sprinkle of fresh herbs.