Put the chicken inside the marinade and mix very well with your hand. Cover and let it rest for 3 hours - overnight.
While the chicken is marinating, soak the skewers in water so it doesn't burn during grilling.
Take out the chicken from the refrigerator about 1 hour before cooking, so it comes to room temperature.
Put the chicken in the wooden skewers. Do not overcrowd the skewer.
Grill on a BBQ grill, if there is no BBG grill, see notes. Grill each side for about 4 mins at 400℉ till cooked through. Cook time will depend on how thick the chicken is.
Remove from the grill.
To make the Tomato Filling
Slice the tomato and onions.
1 large Tomato, 1 medium Onion
Put it inside a bowl and add the oil, oregano, red wine vinegar, salt and black pepper. Mix well and let it sit for 5 mins.
2 tablespoon Olive oil, 1 tablespoon Red wine vinegar, Pinch of Salt, Oregano and Black pepper
To warm the Pita
In a pan, drizzle a little olive oil. When the pan is warm, warm both sides of the pitas till soft, be careful not to use high heat as it will burn and become hard.
Assemble the souvlaki
Place the pita bread on a plate or working surface and add the grilled chicken removed from the skewer, 3 tablespoon of the tomato mix and 1 tablespoon tzatziki sauce.
6 Pita flatbreads, ½ cup Tzatziki sauce
Wrap it and take a big bite. Enjoy.
Notes
Make sure you cut the chicken into cubes such that they're roughly the same size. This way, spices can easily penetrate, and chicken will be cooked evenly without overcooking or being undercooked.
Don't skip the marination time. The chicken should be marinated for at least 3 hours, ideally overnight.
Remember to remove out all the excess water from the shredded cucumber by placing it in a clean muslin cloth and squeezing it out. This will help keep the Tzatziki sauce thick and creamy.
The salad has just tomatoes and onion, which are both high in water content. Season it towards the end to keep them from getting soft and releasing too much water.
If you are serving your pitas right off the grill to eat, then it's fine. But with you preparing them like an hour ahead of them, make sure to cover them with clean cloth. Otherwise, your pita will dry out and become hard and crumbly.
If you are using an Air Fryer, make sure that you let it rest for 10 minutes between batches. It will help it reheat properly.