Season the chicken breast with sea salt, black pepper, and dried oregano on both sides.
Heat a skillet or grill pan over medium-high heat and cook the chicken for 6 to 7 minutes per side until the internal temperature reaches 165°F.
Remove the chicken from the heat and let it rest for 5 minutes before slicing it into bite-sized pieces.
In a small bowl, whisk together the extra virgin olive oil, lemon juice, and minced garlic to create the vinaigrette.
In a large mixing bowl, combine the cooked quinoa, diced cucumber, halved cherry tomatoes, finely minced red onion, and chopped fresh parsley.
Pour the lemon-herb vinaigrette over the quinoa and vegetable mixture, tossing thoroughly to coat.
Add the sliced chicken to the bowl, toss gently to combine, and serve immediately.