Season the chicken breast evenly on both sides with the garlic powder, dried oregano, sea salt, and black pepper.
Heat a non-stick skillet over medium-high heat and cook the chicken for 6 to 7 minutes per side until the exterior is golden brown and the internal temperature reaches 165°F.
While the chicken is cooking, dice the cucumber into bite-sized pieces, halve the cherry tomatoes, and finely mince the red onion.
In a large mixing bowl, whisk together the extra virgin olive oil and fresh lemon juice to create the dressing.
Add the cooked quinoa, diced cucumber, cherry tomatoes, red onion, and chopped fresh parsley to the bowl, tossing thoroughly to ensure everything is coated in the lemon dressing.
Remove the chicken from the pan and let it rest for 3 minutes before slicing it into thin strips.
Transfer the quinoa salad to a serving plate, top with the sliced chicken, and finish by sprinkling the crumbled feta cheese over the top.