While you have time before cooking, prepare all your fresh ingredients: dice the tomatoes into bite-sized pieces, dice the cucumber into 1/2-inch pieces, thinly slice the red onion into half-moons, chop the parsley, and mince the garlic clove. For the tzatziki sauce, grate the remaining cucumber and squeeze it completely dry using a paper towel—this prevents a watery sauce. In a bowl, combine the Greek yogurt, grated cucumber, minced garlic, dill, lemon juice, and fresh mint. Season with a pinch of salt and pepper, then set aside. I like to make the tzatziki ahead so the flavors have time to meld together.
Pat the chicken thighs dry and cut them into 1-inch chunks for even cooking. In a small bowl, combine the oregano, paprika, cumin, garlic powder, salt, and pepper. Coat the chicken pieces generously with this spice mixture, making sure all sides are covered. Heat 3 tablespoons of olive oil in a large pan over medium-high heat until shimmering. Working in batches if needed, brown the chicken on both sides until golden and caramelized, about 4-5 minutes per side. This develops deep flavor through the Maillard reaction. Transfer the browned chicken and any pan juices to a plate and set aside.
Add the remaining 2 tablespoons of olive oil to the same pan and sauté the diced white onion over medium heat for 2 minutes until softened and fragrant. Stir in the rice and toast it for 1-2 minutes, stirring frequently—this helps each grain absorb flavor and cook individually. Meanwhile, in a jug, whisk together the chicken broth, remaining oregano, lemon zest, and lemon juice. Pour the broth mixture into the pan with the rice and stir well. Nestle the browned chicken and its juices on top of the rice, then cover the pan with a lid.
Reduce the heat to medium-low and simmer covered for 20 minutes without lifting the lid. This allows the rice to absorb the broth gradually and cook the chicken through while keeping everything moist and flavorful. The steam trapped under the lid is essential for proper rice cooking. After 20 minutes, remove from heat and let it rest covered for 5 minutes.
Fluff the rice with a fork to separate the grains, incorporating some of the chicken and pan juices throughout. Prepare two bowls and divide the rice and chicken mixture between them. Arrange the diced tomatoes, cucumber, red onion, and crumbled feta on top of the rice in each bowl. Sprinkle the chopped parsley over everything. On the side, place a generous dollop of tzatziki sauce from Step 1 and warm the pita bread. I find that serving the tzatziki on the side lets people control how much they want, rather than mixing it in.
Arrange lemon segments alongside each bowl for extra brightness and acidity. Serve the bowls warm with the tzatziki sauce on the side and warm pita bread for scooping or wrapping. The combination of warm, herb-seasoned rice and chicken with cool, fresh salad components creates a perfect balance of temperatures and flavors.