Puree all the ingredients in a food processor. Chill for a few hours or overnight to allow the flavors to meld
Place the Olive Oil in a large skillet and bring to heat over medium high. Season both sides of the Chicken with the Italian Seasoning plus additional sprinklings of Salt and Black Pepper. Cook 5 minutes per side. Cut the Chicken into thin strips
Soften and warm the Pitas in the microwave for about 20-30 seconds
Place a layer of shredded Lettuce on the Pita and then top with the sliced Chicken, Bell Pepper, Onion and Tomato. Spoon Tzatziki sauce over the top then fold the Pita into a Sandwich.