Slice the chicken: Cut thighs or breasts into thin strips, about 1/2 inch thick.
Thinner pieces cook faster and get better browning.
Mix the marinade: In a bowl, combine olive oil, lemon juice and zest, garlic, Greek yogurt, oregano, cumin, paprika, salt, pepper, and red pepper flakes.
Marinate: Add chicken, toss to coat well, and chill for at least 30 minutes. For deeper flavor, marinate 2–6 hours. Stir once to keep everything coated.
Preheat the air fryer: Set to 380°F (193°C) for 3–5 minutes.
A hot basket helps the chicken sear instead of steam.
Arrange the chicken: Lightly oil the basket or use a perforated liner. Spread chicken in a single layer with some space between pieces. Cook in batches if needed.
Air fry: Cook at 380°F for 8–10 minutes, flipping or shaking halfway.
Chicken is done when edges are browned and the internal temperature hits 165°F (74°C).
Warm the pitas: While the chicken cooks, warm pitas in a dry skillet, microwave, or the air fryer for 1–2 minutes until soft and pliable.
Prep the fillings: Slice cucumbers and onions thin. Chop tomatoes. Crumble feta.
Stir fresh herbs into the tzatziki for extra brightness.
Rest and taste: Let the chicken rest 3 minutes. Taste and finish with a squeeze of lemon and a pinch of salt if needed.
Assemble the gyros: Spread tzatziki on warm pita, add chicken, then top with cucumbers, tomatoes, red onion, and herbs. Finish with feta, a drizzle of olive oil, and a squeeze of lemon.
Serve: Wrap in parchment or foil to hold everything together, and eat while warm.