01 - Preheat oven to 425°F. Line a large sheet pan with parchment paper.
02 - In a bowl, toss chicken pieces with olive oil, smoked paprika, garlic powder, oregano, salt, pepper, and lemon juice until evenly coated.
03 - Place seasoned chicken on one half of the prepared sheet pan in a single layer.
04 - In a separate bowl, toss red onion wedges, bell pepper slices, and cherry tomatoes with olive oil, salt, and pepper.
05 - Spread the seasoned vegetables on the remaining half of the sheet pan, keeping them separate from the chicken.
06 - Roast for 20-25 minutes, stirring halfway through cooking, until chicken is cooked through and vegetables are tender with slight charring.
07 - While chicken and vegetables roast, whisk together mayonnaise, Greek yogurt, parsley, dill, chives, garlic, lemon juice, onion powder, salt, and pepper until smooth and well combined.
08 - Heat pita breads in the oven for 2-3 minutes or in a dry skillet until warm and pliable.
09 - Fill each warmed pita with shredded lettuce, roasted chicken and vegetables, drizzle generously with herby ranch sauce, and top with crumbled feta cheese. Serve immediately.