In a medium bowl, mix together the olive oil, lemon juice, smoked paprika, cumin, garlic, turmeric, coriander, salt, pepper, onion powder, and cinnamon. Add the chicken breast and coat evenly. Let it marinate for 20 minutes.
Prep all ingredients per the instructions above.
To make the tzatziki sauce, combine garlic, cucumber, dill, Greek yogurt, lemon juice, salt, and pepper in a blender. Blend until smooth. Taste and adjust seasoning if needed. Refrigerate until ready to use.
Heat a grill pan or griddle over medium heat.
Remove the chicken from the marinade and let excess liquid drip off. Grill on each side to an internal temperature of 165°F / 74°C. Set aside and let it rest for a few minutes before dicing into bite-sized pieces.
Warm the pita bread for about 30 seconds on each side in the grill pan until soft and pliable.
Fill the pita with lettuce, grilled chicken, red onion, grape tomatoes, olives, feta cheese, and a generous spoonful of tzatziki sauce. Fold in half.
Combine water, lemon juice, and honey or sugar. Stir until dissolved and serve over ice.
Serve the gyro with carrots, hummus, pickle, and lemonade.