In a bowl, whisk together the olive oil, lemon juice, cumin, paprika, coriander, garlic powder, salt, and pepper.
Add the chicken to the bowl and toss to coat well with the marinade. Cover and refrigerate for at least 30 minutes, or up to 2 hours.
Preheat a large skillet or grill pan over medium-high heat. Add the chicken and cook for 5-6 minutes per side, or until cooked through and slightly charred.
Warm the pita bread in the microwave or oven, then fill with the cooked chicken and any desired toppings. Serve immediately.