Pat chicken dry and season all over with oregano, 3/4 teaspoon salt, and pepper. Heat 2 tablespoons olive oil in a large skillet over medium-high heat until shimmering. Add chicken in a single layer and cook undisturbed for 5-6 minutes until golden brown. Flip and cook 4-5 minutes more until cooked through (165°F internal temperature). Transfer to a cutting board to rest for 5 minutes, then slice or chop into bite-sized pieces.

While chicken cooks, bring a large pot of salted water to a boil. Add orzo and cook according to package directions until al dente, usually 8-10 minutes. Drain and rinse briefly under cool water to stop cooking. Shake well to remove excess water and transfer to a large serving bowl.

In a small bowl, whisk together lemon juice, lemon zest, 1/4 cup olive oil, garlic, Dijon mustard, honey, and remaining 1/4 teaspoon salt until emulsified. Prep your vegetables while the orzo cools slightly - dice cucumber, halve tomatoes, pit and halve olives, and finely dice red onion.

Add the warm orzo to a large bowl. Pour about two-thirds of the dressing over it and toss to coat - the warm pasta absorbs flavor beautifully. Add cucumber, tomatoes, olives, red onion, and parsley. Toss gently to combine.

Add the sliced chicken and feta to the bowl. Drizzle with remaining dressing and give everything a final gentle toss. Taste and adjust salt if needed - the olives and feta add plenty of salinity. Serve at room temperature or chilled.