In a medium bowl, combine the chicken thighs with olive oil, dried oregano, garlic powder, smoked paprika, sea salt, and freshly ground black pepper. Toss the ingredients thoroughly to ensure each piece of chicken is evenly coated in the marinade. Allow the chicken to marinate for at least 15 minutes at room temperature, or for up to 2 hours in the refrigerator to enhance the flavors.
Heat a large skillet or grill pan over medium-high heat. Once hot, add the marinated chicken thighs. Cook them for approximately 6-7 minutes on each side, or until the chicken is thoroughly cooked (reaching an internal temperature of 165°F) and has a nice golden-brown sear. Once cooked, remove the chicken from the heat and let it rest for a few minutes before slicing.
After allowing the chicken to cool slightly, slice the chicken thighs into thin, bite-sized strips to make assembling the gyros easier.
In the same skillet or grill pan used for the chicken, lightly warm the pita breads to make them soft and pliable, cooking for about 1 minute on each side. Keep an eye on them to prevent burning.
On each warm pita, spread a generous layer of tzatziki sauce. Top with sliced chicken, then add halved cherry tomatoes, diced cucumber, and thinly sliced red onion for a fresh crunch.
Finish off your gyros by sprinkling fresh parsley leaves on top for an added pop of freshness and color.
To serve, roll up each pita around the delicious fillings, securing everything inside. Provide additional tzatziki on the side for dipping or drizzling as desired.
Notes
Consider serving the gyros on a wooden board lined with parchment paper, accompanied by slices of lemon for squeezing over, and a small bowl of extra tzatziki for dipping.