In a ziploc bag add the Chicken, 2 tbsp Olive Oil, and Greek Seasoning. Let marinate for 30 minutes to an hour.
Remove the chicken from the ziploc bag and place it on a baking sheet. You will cook the chicken at 350ยบ F between 30 - 45 minutes depending on the size of the breasts.
While the chicken is cooking slice the Onions & Peppers. In a frying pan add the remaining Olive Oil and heat up on medium heat. Add the Onions & Peppers to the pan and cook until soft. Once soft remove from heat.
When the chicken is fully cooked remove from the oven and cut it up into chunks.
Now it's time to assemble! On a Pita place the onion and pepper mixture, then the chicken, and finally the tzatziki. If you'd like you can add tomatoes, cucumbers, olives, and lettuce too.