In a gallon size Ziploc bag, combine chicken, olive oil, lemon juice, garlic, oregano, thyme, paprika, 1 teaspoon salt and 1/2 teaspoon pepper. Marinate for at least 2 hours to overnight, turning the bag occasionally. Drain the chicken from the marinade.
Preheat grill to medium heat. Add chicken to grill, and cook, turning occasionally, until chicken is completely cooked through, reaching an internal temperature of 165 degrees F, about 8 minutes.
To serve, warm pitas on the grill, about 1-2 minutes per side. Halve pitas, and fill with chicken, lettuce, tomatoes, onion and tzatziki sauce.
Serve immediately.
For the tzatziki sauce
In a medium bowl, combine Greek yogurt, cucumber, dill, lemon juice, lemon zest and garlic; season with salt and pepper, to taste. Set aside in the refrigerator until ready to serve.
Notes
An outdoor grill is not necessary. Too cold to grill outside? A cast iron grill pan can be used to get those favorited grill marks and charred flavor.
Use chicken breasts. If tenderloins are not readily available at your local supermarket, chicken breasts can be used instead, cut into large strips about 1/2 to 3/4-inch thick.
Marinate overnight. Let the chicken marinate overnight (or at least 2 hours). The longer it sits, the better, really letting the flavors meld and intensify. But avoid marinating longer than 24 hours – the acidic ingredients (lemon juice) can start to break down the chicken, making it mushy.
Preheat the grill. Ensure that the grill is properly cleaned (to prevent sticking) and preheated prior to grilling. This will allow for a better sear for those grill marks and evenly cooked chicken.
Work in batches. An overcrowded grill or pan can lead to uneven cooking and poor browning. Work in batches to maintain high heat for a good sear and crispy crust on each chicken tenderloin.
Use an instant-read thermometer for the most accurate results. The internal temperature should reach 165°F.
Let your meat rest. Let your chicken rest for at least 5 minutes prior to serving, allowing the juices to redistribute – this will allow for maximum flavor and juiciness.
Reheat in the oven. Leftover chicken can be rubbery when reheated. For best results with leftovers, reheat in the oven at 350°F, covered in aluminum foil until warmed through.
Mix it up. Skip the pita bread and transform these wraps into a salad or gyro bowl.