1. In a mixing bowl, combine olive oil, oregano, garlic powder, paprika, salt, and black pepper. Add chicken strips and marinate for at least 15 minutes.
2. Heat a grill pan over medium heat. Cook the chicken strips for about 5-7 minutes on each side until fully cooked.
3. In another bowl, mix Greek yogurt, lemon juice, dill, minced garlic, and grated cucumber to make the tzatziki sauce.
4. Warm the pita bread on the grill pan for about 1 minute on each side.
5. Assemble the gyros by placing chicken strips on the pita bread, adding diced tomato, sliced red onion, and a generous amount of tzatziki sauce.
6. Serve immediately and enjoy!