In a large mixing bowl, combine the thinly sliced chicken breast with extra virgin olive oil, dried oregano, garlic powder, onion powder, and a generous pinch of salt and black pepper. Mix everything thoroughly until the chicken is well coated in the marinade.
Preheat a non-stick skillet or grill pan over medium-high heat. Add the marinated chicken to the pan, spreading it out in a single layer. Cook for approximately 6-7 minutes, turning halfway through, until the chicken is thoroughly cooked and nicely charred with grill marks. Once cooked, remove from heat and let it rest while you prepare the rest of the ingredients.
In a small mixing bowl, whisk together the Greek yogurt, fresh lemon juice, a pinch of salt, and a dash of pepper until smooth and creamy, resembling a tzatziki-like sauce. Adjust seasoning to taste.
To assemble your gyro bowls, start by placing a generous scoop of cooked quinoa or rice at the bottom of each bowl, creating a hearty base.
Next, artfully layer the warm, cooked chicken over the grains, then arrange the diced cucumber, halved cherry tomatoes, thinly sliced red onion, and Kalamata olives on top.
Drizzle a generous amount of the tangy Greek yogurt sauce over the assembled ingredients in each bowl, allowing it to cascade beautifully over the toppings.
Finish by garnishing each bowl with a sprinkle of chopped fresh parsley for added color and a burst of fresh flavor.
If using, serve the gyro bowls with warmed pita bread on the side for scooping and extra enjoyment.