Using a sharp knife, slice the chicken thighs into small, even strips, approximately ½ inch thick. Place them in a medium bowl and season evenly with the salt and pepper. Toss well to coat and set aside.

In a large, deep sauté pan (approximately 10 inches), heat the olive oil over medium-high heat. Once the oil shimmers, add the orzo and cook, stirring frequently, until the pasta is evenly coated and develops a light golden hue, about 2 minutes. The orzo should release a mild, nutty aroma.

Carefully pour the chicken stock, lemon juice, vinegar, and capers (if using) into the pan. Stir well to deglaze, scraping up any bits from the bottom to infuse the orzo with additional flavor. Allow the liquid to come to a rolling boil, then reduce the heat to medium. Maintain a steady simmer and cook for approximately 8 minutes, stirring occasionally to prevent the orzo from sticking.

Once the orzo has softened slightly and the liquid has reduced, add the seasoned chicken to the pan. Stir to distribute evenly, then cover the pan with a fitted lid. Continue cooking over medium heat for 5 minutes, stirring once or twice to ensure even cooking.

Remove the lid and continue simmering uncovered for an additional 8 minutes, or until the orzo is tender and the chicken is cooked through. The liquid should have thickened into a creamy, cohesive sauce. Taste and adjust seasoning with additional salt or lemon juice as desired.

Remove the pan from the heat and stir in the Parmesan cheese until fully melted and incorporated. The sauce should achieve a smooth, glossy consistency that lightly coats the pasta and chicken.

Spoon the Creamy Lemon Chicken Orzo onto warm plates or shallow bowls. Serve immediately, garnished with an extra sprinkle of Parmesan or a wedge of fresh lemon, if desired.