Season the chicken breast evenly with half of the dried oregano, sea salt, and black pepper.
Heat a skillet over medium heat with half of the olive oil and cook the chicken for 6-7 minutes per side until golden and the internal temperature reaches 165 degrees.
While the chicken cooks, dice the cucumber into small cubes, halve the cherry tomatoes, and finely mince the red onion.
In a large mixing bowl, whisk together the remaining olive oil, lemon juice, and the rest of the oregano to create a bright dressing.
Add the cooked quinoa, cucumber, tomatoes, and red onion to the bowl, tossing thoroughly to coat with the dressing.
Slice the cooked chicken into bite-sized strips and gently fold them into the quinoa salad.
Garnish the salad with fresh chopped parsley and serve immediately while the chicken is warm.