Chicken gyro meat: preheat your oven to 400 F (205 C).

Combine all of the chicken gyro ingredients (except for the lemon juice) in a large bowl.

Separate the meat mixture into two halves and place one half right in the middle of a sheet of parchment about 20 inches long. Top the meat with a second similar sized piece of parchment and flatten the meat until it's about a quarter inch thick. Using your hands or a rolling pin, make sure the meat mixture is about the same thickness throughout. 

Remove and discard the top sheet of parchment.

Roll the parchment with the flattened meat mixture on top in about 2-inch wide folds.

Repeat this process with the second half of the meat mixture and two more sheets of parchment. 

Place both parchment-folded meat mixtures on a sheet pan and bake for 18 minutes.

Remove the sheet pan and allow everything to cool for 10 minutes before removing the meat from the parchment and ripping it into smaller pieces or strips. Sprinkle a little lemon juice on top of all of the meat, and at this point, you can make gyros, or you can move the meat to a sealed container into the refrigerator until time to use.

Gyro assembly: In a medium pan over medium heat, warm your pita. This should take only 1 to 2 minutes per side until the pita has softened and is warmed through. 

Remove the pita to a plate and add 1 teaspoon of olive oil to the pan that's still over medium heat. Once the oil has a minute to warm up, add enough meat for your pita and move it around to get the meat covered by the oil. Cook for 1 to 2 minutes per side until the chicken is warmed through and slightly crispy. Now it's time to build the gyro. 

Spread about a tablespoon of tzatziki down the middle of the pita and top it with warmed chicken gyro meat. 

Add slices of tomato and sliced red onion on top of the meat, and then add more tzatziki if desired. Garnish with cilantro or parsley and serve.