In a mixing bowl, combine olive oil, oregano, garlic powder, salt, and pepper to create a marinade. Coat the chicken thighs thoroughly and marinate for at least 30 minutes or overnight.

Heat a skillet over medium-high heat, drizzle olive oil, add marinated chicken, and cook for 5-7 minutes on each side until golden brown and cooked through.

In a medium bowl, mix together Greek yogurt, crumbled feta, lemon juice, minced garlic, salt, and pepper until smooth to make tzatziki sauce.

Once the chicken has rested, slice it into strips.

Warm pita bread, spread a layer of tzatziki, add chicken strips, cherry tomatoes, cucumber, and red onion, then roll up tightly.

Serve immediately, garnished with additional tzatziki and fresh herbs if desired.